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homelab/20251230_first_zfs_degradation.md

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# First ZFS Degradation
## Problem
On 2025-12-30 I was snooping around the Proxmox UI where I accidentally bumped into a storage view that showed that my ZFS pool (which I use for the disks of all my VMs) was in degraded state. Opening up the detail, it appeared one of the disks was in FAULTED state.
I attempted rebooting the host, which triggered an attempt at resilvering. But the disk remained in the same state.
## First diagnostic
After researching a bit, I ran the following diagnostic steps:
- I scanned the kernel logs with `dmesg -T | egrep -i 'ata[0-9]|sata|reset|link|i/o error|blk_update_request|scsi|sense' | tail -200`.
- The logs revealed that the disk connection seemed flaky, with the device reconnecting and going from bein `sdb` to `sdc`. Also, speed was being downgraded sequentially.
- I ran the `smartctl` health assessment and the `smartctl` short test.
- This revealed that the disk looked healthy, and that it was having repeated "Hardware resets". Apparently, this is consistent with the idea that the HDD is repeteadly connecing/disconnecting, as the kernel logs point to.
So, after these, the initial hypothesis is that the drive itself is in good shape, but there is a connection issue. The first candidates are that either the SATA data cable is not working properly, or the power supply to the disk is flickering. If that's not the case, the issue could lie in the SATA port in the motherbase, or some other motherbase issue upstream of the sata port. Finally, it could also be an issue in the PSU.
## First solution attempt
### Plan
With this info, I decide to try to reseat the HDD as a first solution.
Rough plan:
- Pre-action
- Take some vars in:
```
DISKID="$(ls -1 /dev/disk/by-id/ | grep -m1 WX11TN0Z)"
echo "$DISKID"
DISKPATH="/dev/disk/by-id/$DISKID"
echo "$DISKPATH"
```
- Log:
- Serial of the bad drive
- ZFS status: `zpool status -v proxmox-tank-1`
- Kernel log after boot and some minutes of normal operation: `dmesg -T | egrep -i 'ata4|sata|reset|link|exception|interface fatal|failed to IDENTIFY|qc timeout|I/O error|blk_update_request|Not Ready' | tail -200`
- Smartctl output:
```
readlink -f "$DISKPATH"
smartctl -x "$(readlink -f "$DISKPATH")" | egrep -i 'overall|Reallocated|Pending|Offline_Uncorrect|CRC|Error Log|Hardware Resets|COMRESET|SATA Phy'
```
- Reseat
- Remove the disk from the ZFS pool
- Turn it off with `zpool offline proxmox-tank-1 "$DISKID"`
- Check with `zpool status -v proxmox-tank-1`
- Power down the server
- Open up, check the disks. Map out the relation between the name tags and the serial numbers.
- Reseat both the power cable and the data cable of the faulty disk.
- Since we opened up, also check the cables of the other unit.
- Close again, reboot.
- Taking back online and evaluating
- First, check that the OS sees the disk properly:
```
ls -l /dev/disk/by-id/ | grep WX11TN0Z
readlink -f "$DISKPATH"
```
- Start a terminal dedicated to monitoring kernel logs with `dmesg -Tw`. Leave it running while we go for next steps.
- If the disk appears properly and there are no weird signals in kernel logs, add it back into the ZFS pool. Monitor the resilvering process regularly with `zpool status`, and wait for resilvering to finish:
```
zpool online proxmox-tank-1 "$DISKID"
zpool status -v proxmox-tank-1
```
- Run a scrub and monitor the disk state while it happens. Also, pay special attention to the kernel log output, we shouldn't see any SATA resets. The scrub can take an hour or two.
```
zpool scrub proxmox-tank-1
watch -n 5 "zpool status -v proxmox-tank-1"
```
- If ZFS shows no problems, after ~30min of activity, check again with smartctl to evaluate disk health and confirm it's all good:
```
smartctl -x "$(readlink -f "$DISKPATH")" | egrep -i 'Reallocated|Pending|Offline_Uncorrect|CRC|Hardware Resets|COMRESET|SATA Phy'
```
- Decision:
- If outcome was like this:
- No weird kernel log messages.
- ZFS indicates healthy status after resilvering, holds it consistently.
- smartctl reads that disk is healthy.
- Then disk is healthy, cable connection was solved and we're all good.
- If any of the previous was not successful, we're still in trouble. Given outputs, evaluate if we should judge cables, disk or motherboard next.
### Execution notes
- Pre shutdown logs
- Disk ID:
```
DISKID="ata-ST4000NT001-3M2101_WX11TN0Z"
DISKPATH="/dev/disk/by-id/ata-ST4000NT001-3M2101_WX11TN0Z"
```
- ZFS Pool status with `zpool status -v proxmox-tank-1`:
```
pool: proxmox-tank-1
state: DEGRADED
status: One or more devices is currently being resilvered. The pool will
continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
scan: resilver in progress since Fri Jan 2 22:25:31 2026
978G / 1.26T scanned at 1.92G/s, 26.0G / 524G issued at 52.3M/s
0B resilvered, 4.96% done, no estimated completion time
config:
NAME STATE READ WRITE CKSUM
proxmox-tank-1 DEGRADED 0 0 0
mirror-0 DEGRADED 0 0 0
ata-ST4000NT001-3M2101_WX11TN0Z FAULTED 108 639 129 too many errors
ata-ST4000NT001-3M2101_WX11TN2P ONLINE 0 0 0
errors: No known data errors
```
- Kernel logs coming from a clean boot after around 10 min of operation:
```
sudo dmesg -T | egrep -i 'ata4|sata|reset|link|exception|interface fatal|failed to IDENTIFY|qc timeout|I/O error|blk_update_request|Not Ready' | tail -200
[Fri Jan 2 22:25:08 2026] ata4.00: ATA-11: ST4000NT001-3M2101, EN01, max UDMA/133
[Fri Jan 2 22:25:08 2026] ata4.00: 7814037168 sectors, multi 16: LBA48 NCQ (depth 32), AA
[Fri Jan 2 22:25:08 2026] ata4.00: Features: NCQ-sndrcv
[Fri Jan 2 22:25:08 2026] ata4.00: configured for UDMA/133
[Fri Jan 2 22:25:13 2026] ata4.00: exception Emask 0x50 SAct 0x70220001 SErr 0xe0802 action 0x6 frozen
[Fri Jan 2 22:25:13 2026] ata4.00: irq_stat 0x08000000, interface fatal error
[Fri Jan 2 22:25:13 2026] ata4: SError: { RecovComm HostInt PHYInt CommWake 10B8B }
[Fri Jan 2 22:25:13 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:25:13 2026] ata4.00: cmd 60/20:00:98:4e:04/00:00:38:00:00/40 tag 0 ncq dma 16384 in
[Fri Jan 2 22:25:13 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:25:13 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:25:13 2026] ata4.00: cmd 60/00:88:d8:39:00/01:00:38:00:00/40 tag 17 ncq dma 131072 in
[Fri Jan 2 22:25:13 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:25:13 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:25:13 2026] ata4.00: cmd 60/20:a8:98:49:04/00:00:38:00:00/40 tag 21 ncq dma 16384 in
[Fri Jan 2 22:25:13 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:25:13 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:25:13 2026] ata4.00: cmd 60/18:e0:a8:26:d4/00:00:38:00:00/40 tag 28 ncq dma 12288 in
[Fri Jan 2 22:25:13 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:25:13 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:25:13 2026] ata4.00: cmd 60/30:e8:e8:ad:d5/00:00:38:00:00/40 tag 29 ncq dma 24576 in
[Fri Jan 2 22:25:13 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:25:13 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:25:13 2026] ata4.00: cmd 60/00:f0:00:2a:00/01:00:38:00:00/40 tag 30 ncq dma 131072 in
[Fri Jan 2 22:25:13 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:25:13 2026] ata4: hard resetting link
[Fri Jan 2 22:25:14 2026] ata4: SATA link down (SStatus 0 SControl 300)
[Fri Jan 2 22:25:14 2026] ata4: hard resetting link
[Fri Jan 2 22:25:19 2026] ata4: link is slow to respond, please be patient (ready=0)
[Fri Jan 2 22:25:24 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:25:24 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:25:24 2026] ata4: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[Fri Jan 2 22:25:29 2026] ata4.00: qc timeout after 5000 msecs (cmd 0xec)
[Fri Jan 2 22:25:29 2026] ata4.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[Fri Jan 2 22:25:29 2026] ata4.00: revalidation failed (errno=-5)
[Fri Jan 2 22:25:29 2026] ata4: limiting SATA link speed to 3.0 Gbps
[Fri Jan 2 22:25:29 2026] ata4: hard resetting link
[Fri Jan 2 22:25:30 2026] ata4: SATA link up 3.0 Gbps (SStatus 123 SControl 320)
[Fri Jan 2 22:25:30 2026] ata4.00: configured for UDMA/133
[Fri Jan 2 22:25:30 2026] ata4: EH complete
[Fri Jan 2 22:25:33 2026] ata4.00: exception Emask 0x50 SAct 0x30008000 SErr 0xe0802 action 0x6 frozen
[Fri Jan 2 22:25:33 2026] ata4.00: irq_stat 0x08000000, interface fatal error
[Fri Jan 2 22:25:33 2026] ata4: SError: { RecovComm HostInt PHYInt CommWake 10B8B }
[Fri Jan 2 22:25:33 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:25:33 2026] ata4.00: cmd 60/a0:78:30:92:54/00:00:a2:00:00/40 tag 15 ncq dma 81920 in
[Fri Jan 2 22:25:33 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:25:33 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:25:33 2026] ata4.00: cmd 60/40:e0:50:ae:11/00:00:a0:00:00/40 tag 28 ncq dma 32768 in
[Fri Jan 2 22:25:33 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:25:33 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:25:33 2026] ata4.00: cmd 60/68:e8:30:0f:59/02:00:a2:00:00/40 tag 29 ncq dma 315392 in
[Fri Jan 2 22:25:33 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:25:33 2026] ata4: hard resetting link
[Fri Jan 2 22:25:34 2026] ata4: SATA link down (SStatus 0 SControl 320)
[Fri Jan 2 22:25:34 2026] ata4: hard resetting link
[Fri Jan 2 22:25:39 2026] ata4: link is slow to respond, please be patient (ready=0)
[Fri Jan 2 22:25:44 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:25:44 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:25:44 2026] ata4: SATA link up 3.0 Gbps (SStatus 123 SControl 320)
[Fri Jan 2 22:25:49 2026] ata4.00: qc timeout after 5000 msecs (cmd 0xec)
[Fri Jan 2 22:25:49 2026] ata4.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[Fri Jan 2 22:25:49 2026] ata4.00: revalidation failed (errno=-5)
[Fri Jan 2 22:25:49 2026] ata4: limiting SATA link speed to 1.5 Gbps
[Fri Jan 2 22:25:49 2026] ata4: hard resetting link
[Fri Jan 2 22:25:50 2026] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[Fri Jan 2 22:25:50 2026] ata4.00: configured for UDMA/133
[Fri Jan 2 22:25:50 2026] ata4.00: limiting speed to UDMA/100:PIO4
[Fri Jan 2 22:25:51 2026] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[Fri Jan 2 22:25:51 2026] ata4.00: configured for UDMA/100
[Fri Jan 2 22:25:51 2026] ata4: EH complete
[Fri Jan 2 22:25:52 2026] ata4.00: exception Emask 0x50 SAct 0x80001001 SErr 0x20802 action 0x6 frozen
[Fri Jan 2 22:25:52 2026] ata4.00: irq_stat 0x08000000, interface fatal error
[Fri Jan 2 22:25:52 2026] ata4: SError: { RecovComm HostInt PHYInt }
[Fri Jan 2 22:25:52 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:25:52 2026] ata4.00: cmd 60/b8:00:c0:31:57/00:00:94:00:00/40 tag 0 ncq dma 94208 in
[Fri Jan 2 22:25:52 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:25:52 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:25:52 2026] ata4.00: cmd 60/58:60:c0:73:45/00:00:94:00:00/40 tag 12 ncq dma 45056 in
[Fri Jan 2 22:25:52 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:25:52 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:25:52 2026] ata4.00: cmd 60/58:f8:08:72:45/00:00:94:00:00/40 tag 31 ncq dma 45056 in
[Fri Jan 2 22:25:52 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:25:52 2026] ata4: hard resetting link
[Fri Jan 2 22:25:52 2026] ata4: SATA link down (SStatus 0 SControl 310)
[Fri Jan 2 22:25:52 2026] ata4: hard resetting link
[Fri Jan 2 22:25:57 2026] ata4: link is slow to respond, please be patient (ready=0)
[Fri Jan 2 22:26:02 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:26:02 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:26:02 2026] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[Fri Jan 2 22:26:08 2026] ata4.00: qc timeout after 5000 msecs (cmd 0xec)
[Fri Jan 2 22:26:08 2026] ata4.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[Fri Jan 2 22:26:08 2026] ata4.00: revalidation failed (errno=-5)
[Fri Jan 2 22:26:08 2026] ata4: hard resetting link
[Fri Jan 2 22:26:08 2026] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[Fri Jan 2 22:26:08 2026] ata4.00: configured for UDMA/100
[Fri Jan 2 22:26:08 2026] ata4: EH complete
[Fri Jan 2 22:26:10 2026] ata4.00: exception Emask 0x50 SAct 0x1800200 SErr 0x60802 action 0x6 frozen
[Fri Jan 2 22:26:10 2026] ata4.00: irq_stat 0x08000000, interface fatal error
[Fri Jan 2 22:26:10 2026] ata4: SError: { RecovComm HostInt PHYInt CommWake }
[Fri Jan 2 22:26:10 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:26:10 2026] ata4.00: cmd 60/58:48:40:00:09/00:00:7b:00:00/40 tag 9 ncq dma 45056 in
[Fri Jan 2 22:26:10 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:26:10 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:26:10 2026] ata4.00: cmd 60/40:b8:38:53:18/00:00:86:00:00/40 tag 23 ncq dma 32768 in
[Fri Jan 2 22:26:10 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:26:10 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:26:10 2026] ata4.00: cmd 60/58:c0:90:0f:0e/00:00:7f:00:00/40 tag 24 ncq dma 45056 in
[Fri Jan 2 22:26:10 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:26:10 2026] ata4: hard resetting link
[Fri Jan 2 22:26:10 2026] ata4: SATA link down (SStatus 0 SControl 310)
[Fri Jan 2 22:26:10 2026] ata4: hard resetting link
[Fri Jan 2 22:26:15 2026] ata4: link is slow to respond, please be patient (ready=0)
[Fri Jan 2 22:26:20 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:26:20 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:26:20 2026] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[Fri Jan 2 22:26:26 2026] ata4.00: qc timeout after 5000 msecs (cmd 0xec)
[Fri Jan 2 22:26:26 2026] ata4.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[Fri Jan 2 22:26:26 2026] ata4.00: revalidation failed (errno=-5)
[Fri Jan 2 22:26:26 2026] ata4: hard resetting link
[Fri Jan 2 22:26:26 2026] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[Fri Jan 2 22:26:26 2026] ata4.00: configured for UDMA/100
[Fri Jan 2 22:26:26 2026] ata4.00: limiting speed to UDMA/33:PIO4
[Fri Jan 2 22:26:27 2026] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[Fri Jan 2 22:26:27 2026] ata4.00: configured for UDMA/33
[Fri Jan 2 22:26:27 2026] ata4: EH complete
[Fri Jan 2 22:26:28 2026] ata4.00: exception Emask 0x50 SAct 0x800003 SErr 0x20802 action 0x6 frozen
[Fri Jan 2 22:26:28 2026] ata4.00: irq_stat 0x08000000, interface fatal error
[Fri Jan 2 22:26:28 2026] ata4: SError: { RecovComm HostInt PHYInt }
[Fri Jan 2 22:26:28 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:26:28 2026] ata4.00: cmd 60/58:00:f0:f8:23/00:00:ab:00:00/40 tag 0 ncq dma 45056 in
[Fri Jan 2 22:26:28 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:26:28 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:26:28 2026] ata4.00: cmd 60/58:08:80:fa:23/00:00:ab:00:00/40 tag 1 ncq dma 45056 in
[Fri Jan 2 22:26:28 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:26:28 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:26:28 2026] ata4.00: cmd 60/50:b8:48:f8:23/00:00:ab:00:00/40 tag 23 ncq dma 40960 in
[Fri Jan 2 22:26:28 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:26:28 2026] ata4: hard resetting link
[Fri Jan 2 22:26:28 2026] ata4: SATA link down (SStatus 0 SControl 310)
[Fri Jan 2 22:26:28 2026] ata4: hard resetting link
[Fri Jan 2 22:26:33 2026] ata4: link is slow to respond, please be patient (ready=0)
[Fri Jan 2 22:26:38 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:26:38 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:26:38 2026] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[Fri Jan 2 22:26:43 2026] ata4.00: qc timeout after 5000 msecs (cmd 0xec)
[Fri Jan 2 22:26:43 2026] ata4.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[Fri Jan 2 22:26:43 2026] ata4.00: revalidation failed (errno=-5)
[Fri Jan 2 22:26:43 2026] ata4: hard resetting link
[Fri Jan 2 22:26:44 2026] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[Fri Jan 2 22:26:44 2026] ata4.00: configured for UDMA/33
[Fri Jan 2 22:26:44 2026] ata4: EH complete
[Fri Jan 2 22:26:45 2026] ata4.00: exception Emask 0x50 SAct 0x801080 SErr 0x60802 action 0x6 frozen
[Fri Jan 2 22:26:45 2026] ata4.00: irq_stat 0x08000000, interface fatal error
[Fri Jan 2 22:26:45 2026] ata4: SError: { RecovComm HostInt PHYInt CommWake }
[Fri Jan 2 22:26:45 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:26:45 2026] ata4.00: cmd 60/50:38:18:df:c5/00:00:a8:01:00/40 tag 7 ncq dma 40960 in
[Fri Jan 2 22:26:45 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:26:45 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:26:45 2026] ata4.00: cmd 60/58:60:98:a0:33/00:00:a9:01:00/40 tag 12 ncq dma 45056 in
[Fri Jan 2 22:26:45 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:26:45 2026] ata4.00: failed command: READ FPDMA QUEUED
[Fri Jan 2 22:26:45 2026] ata4.00: cmd 60/58:b8:a0:e5:b9/00:00:1b:00:00/40 tag 23 ncq dma 45056 in
[Fri Jan 2 22:26:45 2026] ata4.00: status: { DRDY }
[Fri Jan 2 22:26:45 2026] ata4: hard resetting link
[Fri Jan 2 22:26:45 2026] ata4: SATA link down (SStatus 0 SControl 310)
[Fri Jan 2 22:26:45 2026] ata4: hard resetting link
[Fri Jan 2 22:26:50 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:26:50 2026] ata4: SATA link down (SStatus 0 SControl 310)
[Fri Jan 2 22:26:51 2026] ata4: hard resetting link
[Fri Jan 2 22:26:56 2026] ata4: link is slow to respond, please be patient (ready=0)
[Fri Jan 2 22:27:01 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:27:01 2026] ata4: found unknown device (class 0)
[Fri Jan 2 22:27:01 2026] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[Fri Jan 2 22:27:06 2026] ata4.00: qc timeout after 5000 msecs (cmd 0xec)
[Fri Jan 2 22:27:06 2026] ata4.00: failed to IDENTIFY (I/O error, err_mask=0x4)
[Fri Jan 2 22:27:06 2026] ata4.00: revalidation failed (errno=-5)
[Fri Jan 2 22:27:06 2026] ata4.00: disable device
[Fri Jan 2 22:27:07 2026] ata4: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[Fri Jan 2 22:27:07 2026] ata4.00: ATA-11: ST4000NT001-3M2101, EN01, max UDMA/133
[Fri Jan 2 22:27:07 2026] ata4.00: 7814037168 sectors, multi 16: LBA48 NCQ (depth 32), AA
[Fri Jan 2 22:27:07 2026] ata4.00: Features: NCQ-sndrcv
[Fri Jan 2 22:27:07 2026] ata4.00: configured for UDMA/133
[Fri Jan 2 22:27:07 2026] sd 3:0:0:0: [sdb] tag#7 Sense Key : Not Ready [current]
[Fri Jan 2 22:27:07 2026] sd 3:0:0:0: [sdb] tag#7 Add. Sense: Logical unit not ready, hard reset required
[Fri Jan 2 22:27:07 2026] I/O error, dev sdb, sector 7126507288 op 0x0:(READ) flags 0x0 phys_seg 2 prio class 0
[Fri Jan 2 22:27:07 2026] sd 3:0:0:0: [sdb] tag#12 Sense Key : Not Ready [current]
[Fri Jan 2 22:27:07 2026] sd 3:0:0:0: [sdb] tag#12 Add. Sense: Logical unit not ready, hard reset required
[Fri Jan 2 22:27:07 2026] I/O error, dev sdb, sector 7133700248 op 0x0:(READ) flags 0x0 phys_seg 3 prio class 0
[Fri Jan 2 22:27:07 2026] I/O error, dev sdb, sector 630388008 op 0x0:(READ) flags 0x0 phys_seg 3 prio class 0
[Fri Jan 2 22:27:07 2026] sd 3:0:0:0: [sdb] tag#23 Sense Key : Not Ready [current]
[Fri Jan 2 22:27:07 2026] sd 3:0:0:0: [sdb] tag#23 Add. Sense: Logical unit not ready, hard reset required
[Fri Jan 2 22:27:07 2026] I/O error, dev sdb, sector 465167776 op 0x0:(READ) flags 0x0 phys_seg 3 prio class 0
[Fri Jan 2 22:27:07 2026] I/O error, dev sdb, sector 2576 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[Fri Jan 2 22:27:07 2026] I/O error, dev sdb, sector 1847276792 op 0x0:(READ) flags 0x0 phys_seg 14 prio class 0
[Fri Jan 2 22:27:07 2026] I/O error, dev sdb, sector 7814018064 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[Fri Jan 2 22:27:07 2026] ata4: EH complete
[Fri Jan 2 22:27:07 2026] ata4.00: detaching (SCSI 3:0:0:0)
[Fri Jan 2 22:27:07 2026] I/O error, dev sdb, sector 1847277304 op 0x0:(READ) flags 0x0 phys_seg 3 prio class 0
[Fri Jan 2 22:28:39 2026] r8169 0000:07:00.0 eno1: Link is Down
[Fri Jan 2 22:28:42 2026] r8169 0000:07:00.0 eno1: Link is Up - 1Gbps/Full - flow control off
```
- Outputs of suggested smartctl command:
```
SMART overall-health self-assessment test result: PASSED
Error logging capability: (0x01) Error logging supported.
5 Reallocated_Sector_Ct PO--CK 100 100 010 - 0
197 Current_Pending_Sector -O--C- 100 100 000 - 0
198 Offline_Uncorrectable ----C- 100 100 000 - 0
199 UDMA_CRC_Error_Count -OSRCK 200 200 000 - 0
0x01 SL R/O 1 Summary SMART error log
0x02 SL R/O 5 Comprehensive SMART error log
0x03 GPL R/O 5 Ext. Comprehensive SMART error log
0x0c GPL R/O 2048 Pending Defects log
0x10 GPL R/O 1 NCQ Command Error log
0x11 GPL R/O 1 SATA Phy Event Counters log
0x21 GPL R/O 1 Write stream error log
0x22 GPL R/O 1 Read stream error log
SMART Extended Comprehensive Error Log Version: 1 (5 sectors)
If Selective self-test is pending on power-up, resume after 0 minute delay.
0x03 0x020 4 0 --- Number of Reallocated Logical Sectors
0x06 0x008 4 39 --- Number of Hardware Resets
0x06 0x018 4 0 --- Number of Interface CRC Errors
Pending Defects log (GP Log 0x0c)
SATA Phy Event Counters (GP Log 0x11)
0x000a 2 2 Device-to-host register FISes sent due to a COMRESET
0x0001 2 0 Command failed due to ICRC error
```
- Turning off the disk:
- Ran `sudo zpool offline proxmox-tank-1 "$DISKID"`.
- Once finished, status read:
```
pool: proxmox-tank-1
state: DEGRADED
status: One or more devices is currently being resilvered. The pool will
continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
scan: resilver in progress since Fri Jan 2 22:25:31 2026
1.04T / 1.26T scanned at 1.14G/s, 96.2G / 523G issued at 106M/s
0B resilvered, 18.41% done, no estimated completion time
config:
NAME STATE READ WRITE CKSUM
proxmox-tank-1 DEGRADED 0 0 0
mirror-0 DEGRADED 0 0 0
ata-ST4000NT001-3M2101_WX11TN0Z OFFLINE 108 639 129
ata-ST4000NT001-3M2101_WX11TN2P ONLINE 0 0 0
```
- Reseating
- I opened up the case. Generally it looked as if everything was properly seated. I revied the power and data ports on the disk, the power connection to the PSU tread and the data connection to the motherboard. Perhaps the faulty disk power port might have been sliiiiiightly loose, but not that much. All pins were clearly contacting. To be honest, it didn't look like it wasn't properly seated.
- In any case, I reaseted both of the connectors on the disk, and also the motherboard data one.
- Booting again
- Is the disk detected?
- `ls -l /dev/disk/by-id/ | grep WX11TN0Z` shows the disk is using `sdb`.
- `readlink -f "$DISKPATH"` agrees.
- First check of `dmesg` shows the disk succesfully detected and attached as a SCSI drive. No more logs.
- Adding the disk back to the pool
- I add the disk back with `sudo zpool online proxmox-tank-1 "$DISKID"`
- First status right after
```
pool: proxmox-tank-1
state: DEGRADED
status: One or more devices is currently being resilvered. The pool will
continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
scan: resilver in progress since Fri Jan 2 23:17:35 2026
759G / 1.26T scanned at 8.43G/s, 0B / 618G issued
0B resilvered, 0.00% done, no estimated completion time
config:
NAME STATE READ WRITE CKSUM
proxmox-tank-1 DEGRADED 0 0 0
mirror-0 DEGRADED 0 0 0
ata-ST4000NT001-3M2101_WX11TN0Z DEGRADED 0 0 0 too many errors
ata-ST4000NT001-3M2101_WX11TN2P ONLINE 0 0 0
errors: No known data errors
```
- It shows degraded, but 0 errors. I guess that's good news.
- Printing multiple times shows the resilvering process is ongoing and progressing. I'll let that run for a while.
- The writing part of the resilvering begins and the disk still shows 0 errors in the ZFS status. The kernel logs are quiet. The resilvering will take a while: the lagging disk must catch up on 524Gb of content. Dear god, for how long was that disk faulty???
- The writing side of the resilvering is running at ~50MB/s. I'll shut down all the VMs in hopes of preventing contention for the disk IO.
- After around 30min, speed has increased to 100MB/s.
- The resilvering will take a long time and it's late, so I'l go to sleep and continue tomorrow.
- The next morning, status read this:
```
pool: proxmox-tank-1
state: DEGRADED
status: One or more devices has experienced an unrecoverable error. An
attempt was made to correct the error. Applications are unaffected.
action: Determine if the device needs to be replaced, and clear the errors
using 'zpool clear' or replace the device with 'zpool replace'.
see: https://openzfs.github.io/openzfs-docs/msg/ZFS-8000-9P
scan: resilvered 495G in 01:07:58 with 0 errors on Sat Jan 3 00:25:33 2026
config:
NAME STATE READ WRITE CKSUM
proxmox-tank-1 DEGRADED 0 0 0
mirror-0 DEGRADED 0 0 0
ata-ST4000NT001-3M2101_WX11TN0Z DEGRADED 0 0 0 too many errors
ata-ST4000NT001-3M2101_WX11TN2P ONLINE 0 0 0
errors: No known data errors
```
- Apparently, after a little crisis like the one this disk had, ZFS will only mark it clear with human acknowledgement.
- To do that, I run: `zpool clear proxmox-tank-1 ata-ST4000NT001-3M2101_WX11TN0Z`
- Status immediately becomes:
```
pool: proxmox-tank-1
state: ONLINE
scan: resilvered 495G in 01:07:58 with 0 errors on Sat Jan 3 00:25:33 2026
config:
NAME STATE READ WRITE CKSUM
proxmox-tank-1 ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
ata-ST4000NT001-3M2101_WX11TN0Z ONLINE 0 0 0
ata-ST4000NT001-3M2101_WX11TN2P ONLINE 0 0 0
errors: No known data errors
```
- Scrubbing
- I trigger the scrub with: `sudo zpool scrub proxmox-tank-1`
- This is the final message once the scrub finished:
```
pool: proxmox-tank-1
state: ONLINE
status: One or more devices has experienced an unrecoverable error. An
attempt was made to correct the error. Applications are unaffected.
action: Determine if the device needs to be replaced, and clear the errors
using 'zpool clear' or replace the device with 'zpool replace'.
see: https://openzfs.github.io/openzfs-docs/msg/ZFS-8000-9P
scan: scrub repaired 13.0M in 02:14:22 with 0 errors on Sat Jan 3 11:03:54 2026
config:
NAME STATE READ WRITE CKSUM
proxmox-tank-1 ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
ata-ST4000NT001-3M2101_WX11TN0Z ONLINE 0 0 992
ata-ST4000NT001-3M2101_WX11TN2P ONLINE 0 0 0
errors: No known data errors
```
- I clear the error messages with `zpool clear proxmox-tank-1 ata-ST4000NT001-3M2101_WX11TN0Z`
- Nevertheless, those checksum errors might be of concern.
- Checking disk with smartctl
- I run `smartctl -x "$(readlink -f "$DISKPATH")" | egrep -i 'Reallocated|Pending|Offline_Uncorrect|CRC|Hardware Resets|COMRESET|SATA Phy'` and get back:
```
5 Reallocated_Sector_Ct PO--CK 100 100 010 - 0
197 Current_Pending_Sector -O--C- 100 100 000 - 0
198 Offline_Uncorrectable ----C- 100 100 000 - 0
199 UDMA_CRC_Error_Count -OSRCK 200 200 000 - 0
0x0c GPL R/O 2048 Pending Defects log
0x11 GPL R/O 1 SATA Phy Event Counters log
If Selective self-test is pending on power-up, resume after 0 minute delay.
0x03 0x020 4 0 --- Number of Reallocated Logical Sectors
0x06 0x008 4 41 --- Number of Hardware Resets
0x06 0x018 4 0 --- Number of Interface CRC Errors
Pending Defects log (GP Log 0x0c)
SATA Phy Event Counters (GP Log 0x11)
0x000a 2 2 Device-to-host register FISes sent due to a COMRESET
0x0001 2 0 Command failed due to ICRC error
```
- The full output of `smartctl -x /dev/sdb`:
```
smartctl 7.4 2024-10-15 r5620 [x86_64-linux-6.14.8-2-pve] (local build)
Copyright (C) 2002-23, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Device Model: ST4000NT001-3M2101
Serial Number: WX11TN0Z
LU WWN Device Id: 5 000c50 0fb8869af
Firmware Version: EN01
User Capacity: 4,000,787,030,016 bytes [4.00 TB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Rotation Rate: 7200 rpm
Form Factor: 3.5 inches
Device is: Not in smartctl database 7.3/5528
ATA Version is: ACS-4 (minor revision not indicated)
SATA Version is: SATA 3.3, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is: Sat Jan 3 11:16:38 2026 CET
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
AAM feature is: Unavailable
APM feature is: Unavailable
Rd look-ahead is: Enabled
Write cache is: Enabled
DSN feature is: Disabled
ATA Security is: Disabled, NOT FROZEN [SEC1]
Write SCT (Get) Feature Control Command failed: scsi error unsupported field in scsi command
Wt Cache Reorder: Unknown (SCT Feature Control command failed)
=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
General SMART Values:
Offline data collection status: (0x82) Offline data collection activity
was completed without error.
Auto Offline Data Collection: Enabled.
Self-test execution status: ( 0) The previous self-test routine completed
without error or no self-test has ever
been run.
Total time to complete Offline
data collection: ( 567) seconds.
Offline data collection
capabilities: (0x7b) SMART execute Offline immediate.
Auto Offline data collection on/off support.
Suspend Offline collection upon new
command.
Offline surface scan supported.
Self-test supported.
Conveyance Self-test supported.
Selective Self-test supported.
SMART capabilities: (0x0003) Saves SMART data before entering
power-saving mode.
Supports SMART auto save timer.
Error logging capability: (0x01) Error logging supported.
General Purpose Logging supported.
Short self-test routine
recommended polling time: ( 1) minutes.
Extended self-test routine
recommended polling time: ( 372) minutes.
Conveyance self-test routine
recommended polling time: ( 2) minutes.
SCT capabilities: (0x50bd) SCT Status supported.
SCT Error Recovery Control supported.
SCT Feature Control supported.
SCT Data Table supported.
SMART Attributes Data Structure revision number: 10
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAGS VALUE WORST THRESH FAIL RAW_VALUE
1 Raw_Read_Error_Rate POSR-- 080 064 044 - 89842680
3 Spin_Up_Time PO---- 097 093 000 - 0
4 Start_Stop_Count -O--CK 100 100 020 - 237
5 Reallocated_Sector_Ct PO--CK 100 100 010 - 0
7 Seek_Error_Rate POSR-- 078 060 045 - 58464314
9 Power_On_Hours -O--CK 099 099 000 - 1551
10 Spin_Retry_Count PO--C- 100 100 097 - 0
12 Power_Cycle_Count -O--CK 100 100 020 - 237
18 Unknown_Attribute PO-R-- 100 100 050 - 0
187 Reported_Uncorrect -O--CK 100 100 000 - 0
188 Command_Timeout -O--CK 100 100 000 - 0
190 Airflow_Temperature_Cel -O---K 060 054 000 - 40 (Min/Max 26/43)
192 Power-Off_Retract_Count -O--CK 100 100 000 - 229
193 Load_Cycle_Count -O--CK 100 100 000 - 1964
194 Temperature_Celsius -O---K 040 046 000 - 40 (0 23 0 0 0)
197 Current_Pending_Sector -O--C- 100 100 000 - 0
198 Offline_Uncorrectable ----C- 100 100 000 - 0
199 UDMA_CRC_Error_Count -OSRCK 200 200 000 - 0
240 Head_Flying_Hours ------ 100 100 000 - 516 (189 160 0)
241 Total_LBAs_Written ------ 100 253 000 - 19110016931
242 Total_LBAs_Read ------ 100 253 000 - 9057450849
||||||_ K auto-keep
|||||__ C event count
||||___ R error rate
|||____ S speed/performance
||_____ O updated online
|______ P prefailure warning
General Purpose Log Directory Version 1
SMART Log Directory Version 1 [multi-sector log support]
Address Access R/W Size Description
0x00 GPL,SL R/O 1 Log Directory
0x01 SL R/O 1 Summary SMART error log
0x02 SL R/O 5 Comprehensive SMART error log
0x03 GPL R/O 5 Ext. Comprehensive SMART error log
0x04 GPL R/O 256 Device Statistics log
0x04 SL R/O 8 Device Statistics log
0x06 SL R/O 1 SMART self-test log
0x07 GPL R/O 1 Extended self-test log
0x08 GPL R/O 2 Power Conditions log
0x09 SL R/W 1 Selective self-test log
0x0a GPL R/W 8 Device Statistics Notification
0x0c GPL R/O 2048 Pending Defects log
0x10 GPL R/O 1 NCQ Command Error log
0x11 GPL R/O 1 SATA Phy Event Counters log
0x13 GPL R/O 1 SATA NCQ Send and Receive log
0x21 GPL R/O 1 Write stream error log
0x22 GPL R/O 1 Read stream error log
0x24 GPL R/O 768 Current Device Internal Status Data log
0x2f GPL R/O 1 Set Sector Configuration
0x30 GPL,SL R/O 9 IDENTIFY DEVICE data log
0x80-0x9f GPL,SL R/W 16 Host vendor specific log
0xa1 GPL,SL VS 160 Device vendor specific log
0xa2 GPL VS 16320 Device vendor specific log
0xa4 GPL,SL VS 160 Device vendor specific log
0xa6 GPL VS 192 Device vendor specific log
0xa8-0xa9 GPL,SL VS 136 Device vendor specific log
0xab GPL VS 1 Device vendor specific log
0xad GPL VS 16 Device vendor specific log
0xb1 GPL,SL VS 160 Device vendor specific log
0xb6 GPL VS 1920 Device vendor specific log
0xbe-0xbf GPL VS 65535 Device vendor specific log
0xc1 GPL,SL VS 8 Device vendor specific log
0xc3 GPL,SL VS 24 Device vendor specific log
0xc6 GPL VS 5184 Device vendor specific log
0xc7 GPL,SL VS 8 Device vendor specific log
0xc9 GPL,SL VS 8 Device vendor specific log
0xca GPL,SL VS 16 Device vendor specific log
0xcd GPL,SL VS 1 Device vendor specific log
0xce GPL VS 1 Device vendor specific log
0xcf GPL VS 512 Device vendor specific log
0xd1 GPL VS 656 Device vendor specific log
0xd2 GPL VS 10256 Device vendor specific log
0xd4 GPL VS 2048 Device vendor specific log
0xda GPL,SL VS 1 Device vendor specific log
0xe0 GPL,SL R/W 1 SCT Command/Status
0xe1 GPL,SL R/W 1 SCT Data Transfer
SMART Extended Comprehensive Error Log Version: 1 (5 sectors)
No Errors Logged
SMART Extended Self-test Log Version: 1 (1 sectors)
Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error
# 1 Short offline Completed without error 00% 1462 -
SMART Selective self-test log data structure revision number 1
SPAN MIN_LBA MAX_LBA CURRENT_TEST_STATUS
1 0 0 Not_testing
2 0 0 Not_testing
3 0 0 Not_testing
4 0 0 Not_testing
5 0 0 Not_testing
Selective self-test flags (0x0):
After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.
SCT Status Version: 3
SCT Version (vendor specific): 522 (0x020a)
Device State: Active (0)
Current Temperature: 40 Celsius
Power Cycle Min/Max Temperature: 26/43 Celsius
Lifetime Min/Max Temperature: 23/46 Celsius
Under/Over Temperature Limit Count: 0/2
SMART Status: 0xc24f (PASSED)
Vendor specific:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 03 00 00 00 00 00 00 00 00 00 00 00
SCT Temperature History Version: 2
Temperature Sampling Period: 4 minutes
Temperature Logging Interval: 59 minutes
Min/Max recommended Temperature: 10/40 Celsius
Min/Max Temperature Limit: 5/60 Celsius
Temperature History Size (Index): 128 (123)
Index Estimated Time Temperature Celsius
124 2025-12-29 05:52 34 ***************
125 2025-12-29 06:51 34 ***************
126 2025-12-29 07:50 33 **************
... ..( 3 skipped). .. **************
2 2025-12-29 11:46 33 **************
3 2025-12-29 12:45 35 ****************
4 2025-12-29 13:44 35 ****************
5 2025-12-29 14:43 35 ****************
6 2025-12-29 15:42 ? -
7 2025-12-29 16:41 36 *****************
8 2025-12-29 17:40 ? -
9 2025-12-29 18:39 36 *****************
10 2025-12-29 19:38 ? -
11 2025-12-29 20:37 36 *****************
12 2025-12-29 21:36 36 *****************
13 2025-12-29 22:35 35 ****************
... ..( 4 skipped). .. ****************
18 2025-12-30 03:30 35 ****************
19 2025-12-30 04:29 34 ***************
... ..( 2 skipped). .. ***************
22 2025-12-30 07:26 34 ***************
23 2025-12-30 08:25 33 **************
24 2025-12-30 09:24 33 **************
25 2025-12-30 10:23 33 **************
26 2025-12-30 11:22 32 *************
... ..( 3 skipped). .. *************
30 2025-12-30 15:18 32 *************
31 2025-12-30 16:17 33 **************
32 2025-12-30 17:16 33 **************
33 2025-12-30 18:15 32 *************
... ..( 10 skipped). .. *************
44 2025-12-31 05:04 32 *************
45 2025-12-31 06:03 31 ************
... ..( 5 skipped). .. ************
51 2025-12-31 11:57 31 ************
52 2025-12-31 12:56 30 ***********
... ..( 8 skipped). .. ***********
61 2025-12-31 21:47 30 ***********
62 2025-12-31 22:46 31 ************
... ..( 3 skipped). .. ************
66 2026-01-01 02:42 31 ************
67 2026-01-01 03:41 30 ***********
... ..( 10 skipped). .. ***********
78 2026-01-01 14:30 30 ***********
79 2026-01-01 15:29 29 **********
80 2026-01-01 16:28 29 **********
81 2026-01-01 17:27 29 **********
82 2026-01-01 18:26 30 ***********
83 2026-01-01 19:25 29 **********
84 2026-01-01 20:24 29 **********
85 2026-01-01 21:23 29 **********
86 2026-01-01 22:22 30 ***********
87 2026-01-01 23:21 30 ***********
88 2026-01-02 00:20 32 *************
89 2026-01-02 01:19 33 **************
90 2026-01-02 02:18 33 **************
91 2026-01-02 03:17 33 **************
92 2026-01-02 04:16 32 *************
93 2026-01-02 05:15 31 ************
94 2026-01-02 06:14 ? -
95 2026-01-02 07:13 30 ***********
96 2026-01-02 08:12 ? -
97 2026-01-02 09:11 30 ***********
98 2026-01-02 10:10 ? -
99 2026-01-02 11:09 30 ***********
100 2026-01-02 12:08 ? -
101 2026-01-02 13:07 30 ***********
102 2026-01-02 14:06 ? -
103 2026-01-02 15:05 30 ***********
104 2026-01-02 16:04 ? -
105 2026-01-02 17:03 30 ***********
106 2026-01-02 18:02 ? -
107 2026-01-02 19:01 31 ************
108 2026-01-02 20:00 ? -
109 2026-01-02 20:59 31 ************
110 2026-01-02 21:58 ? -
111 2026-01-02 22:57 26 *******
112 2026-01-02 23:56 38 *******************
113 2026-01-03 00:55 36 *****************
114 2026-01-03 01:54 34 ***************
115 2026-01-03 02:53 33 **************
... ..( 4 skipped). .. **************
120 2026-01-03 07:48 33 **************
121 2026-01-03 08:47 37 ******************
122 2026-01-03 09:46 42 ***********************
123 2026-01-03 10:45 43 ************************
SCT Error Recovery Control:
Read: 70 (7.0 seconds)
Write: 70 (7.0 seconds)
Device Statistics (GP Log 0x04)
Page Offset Size Value Flags Description
0x01 ===== = = === == General Statistics (rev 1) ==
0x01 0x008 4 237 --- Lifetime Power-On Resets
0x01 0x010 4 1551 --- Power-on Hours
0x01 0x018 6 18855234811 --- Logical Sectors Written
0x01 0x020 6 38962968 --- Number of Write Commands
0x01 0x028 6 9004753896 --- Logical Sectors Read
0x01 0x030 6 148517033 --- Number of Read Commands
0x01 0x038 6 - --- Date and Time TimeStamp
0x03 ===== = = === == Rotating Media Statistics (rev 1) ==
0x03 0x008 4 1203 --- Spindle Motor Power-on Hours
0x03 0x010 4 516 --- Head Flying Hours
0x03 0x018 4 1964 --- Head Load Events
0x03 0x020 4 0 --- Number of Reallocated Logical Sectors
0x03 0x028 4 0 --- Read Recovery Attempts
0x03 0x030 4 0 --- Number of Mechanical Start Failures
0x03 0x038 4 0 --- Number of Realloc. Candidate Logical Sectors
0x03 0x040 4 229 --- Number of High Priority Unload Events
0x04 ===== = = === == General Errors Statistics (rev 1) ==
0x04 0x008 4 0 --- Number of Reported Uncorrectable Errors
0x04 0x010 4 0 --- Resets Between Cmd Acceptance and Completion
0x04 0x018 4 0 -D- Physical Element Status Changed
0x05 ===== = = === == Temperature Statistics (rev 1) ==
0x05 0x008 1 40 --- Current Temperature
0x05 0x010 1 32 --- Average Short Term Temperature
0x05 0x018 1 34 --- Average Long Term Temperature
0x05 0x020 1 46 --- Highest Temperature
0x05 0x028 1 27 --- Lowest Temperature
0x05 0x030 1 43 --- Highest Average Short Term Temperature
0x05 0x038 1 30 --- Lowest Average Short Term Temperature
0x05 0x040 1 34 --- Highest Average Long Term Temperature
0x05 0x048 1 34 --- Lowest Average Long Term Temperature
0x05 0x050 4 0 --- Time in Over-Temperature
0x05 0x058 1 60 --- Specified Maximum Operating Temperature
0x05 0x060 4 0 --- Time in Under-Temperature
0x05 0x068 1 5 --- Specified Minimum Operating Temperature
0x06 ===== = = === == Transport Statistics (rev 1) ==
0x06 0x008 4 41 --- Number of Hardware Resets
0x06 0x010 4 8 --- Number of ASR Events
0x06 0x018 4 0 --- Number of Interface CRC Errors
0xff ===== = = === == Vendor Specific Statistics (rev 1) ==
0xff 0x010 7 0 --- Vendor Specific
0xff 0x018 7 0 --- Vendor Specific
|||_ C monitored condition met
||__ D supports DSN
|___ N normalized value
Pending Defects log (GP Log 0x0c)
No Defects Logged
SATA Phy Event Counters (GP Log 0x11)
ID Size Value Description
0x000a 2 2 Device-to-host register FISes sent due to a COMRESET
0x0001 2 0 Command failed due to ICRC error
0x0003 2 0 R_ERR response for device-to-host data FIS
0x0004 2 0 R_ERR response for host-to-device data FIS
0x0006 2 0 R_ERR response for device-to-host non-data FIS
0x0007 2 0 R_ERR response for host-to-device non-data FIS
Seagate FARM log (GP Log 0xa6) supported [try: -l farm]
```
- `smartctl -l error` shows no errors.
- `smartctl -l selftest` after triggering the short test:
```
smartctl 7.4 2024-10-15 r5620 [x86_64-linux-6.14.8-2-pve] (local build)
Copyright (C) 2002-23, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF READ SMART DATA SECTION ===
SMART Self-test log structure revision number 1
Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error
# 1 Short offline Completed without error 00% 1551 -
# 2 Short offline Completed without error 00% 1462 -
```
- Then I run the longtest. It will be finished at 18:00.
- While the test runs, I start raising the host VMs again since they can run in parallel.
- The selftest is taking way longer than initially planned, but it's progressing. It's 21:00, 20% remaining.
- It finished eventually. Here's the full output:
```
smartctl 7.4 2024-10-15 r5620 [x86_64-linux-6.14.8-2-pve] (local build)
Copyright (C) 2002-23, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Device Model: ST4000NT001-3M2101
Serial Number: WX11TN0Z
LU WWN Device Id: 5 000c50 0fb8869af
Firmware Version: EN01
User Capacity: 4,000,787,030,016 bytes [4.00 TB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Rotation Rate: 7200 rpm
Form Factor: 3.5 inches
Device is: Not in smartctl database 7.3/5528
ATA Version is: ACS-4 (minor revision not indicated)
SATA Version is: SATA 3.3, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is: Sat Jan 3 23:48:15 2026 CET
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
AAM feature is: Unavailable
APM feature is: Unavailable
Rd look-ahead is: Enabled
Write cache is: Enabled
DSN feature is: Disabled
ATA Security is: Disabled, NOT FROZEN [SEC1]
Write SCT (Get) Feature Control Command failed: scsi error unsupported field in scsi command
Wt Cache Reorder: Unknown (SCT Feature Control command failed)
=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
General SMART Values:
Offline data collection status: (0x82) Offline data collection activity
was completed without error.
Auto Offline Data Collection: Enabled.
Self-test execution status: ( 0) The previous self-test routine completed
without error or no self-test has ever
been run.
Total time to complete Offline
data collection: ( 567) seconds.
Offline data collection
capabilities: (0x7b) SMART execute Offline immediate.
Auto Offline data collection on/off support.
Suspend Offline collection upon new
command.
Offline surface scan supported.
Self-test supported.
Conveyance Self-test supported.
Selective Self-test supported.
SMART capabilities: (0x0003) Saves SMART data before entering
power-saving mode.
Supports SMART auto save timer.
Error logging capability: (0x01) Error logging supported.
General Purpose Logging supported.
Short self-test routine
recommended polling time: ( 1) minutes.
Extended self-test routine
recommended polling time: ( 372) minutes.
Conveyance self-test routine
recommended polling time: ( 2) minutes.
SCT capabilities: (0x50bd) SCT Status supported.
SCT Error Recovery Control supported.
SCT Feature Control supported.
SCT Data Table supported.
SMART Attributes Data Structure revision number: 10
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAGS VALUE WORST THRESH FAIL RAW_VALUE
1 Raw_Read_Error_Rate POSR-- 082 064 044 - 160614704
3 Spin_Up_Time PO---- 097 093 000 - 0
4 Start_Stop_Count -O--CK 100 100 020 - 237
5 Reallocated_Sector_Ct PO--CK 100 100 010 - 0
7 Seek_Error_Rate POSR-- 078 060 045 - 63053692
9 Power_On_Hours -O--CK 099 099 000 - 1564
10 Spin_Retry_Count PO--C- 100 100 097 - 0
12 Power_Cycle_Count -O--CK 100 100 020 - 237
18 Unknown_Attribute PO-R-- 100 100 050 - 0
187 Reported_Uncorrect -O--CK 100 100 000 - 0
188 Command_Timeout -O--CK 100 100 000 - 0
190 Airflow_Temperature_Cel -O---K 063 054 000 - 37 (Min/Max 26/45)
192 Power-Off_Retract_Count -O--CK 100 100 000 - 229
193 Load_Cycle_Count -O--CK 100 100 000 - 1965
194 Temperature_Celsius -O---K 037 046 000 - 37 (0 23 0 0 0)
197 Current_Pending_Sector -O--C- 100 100 000 - 0
198 Offline_Uncorrectable ----C- 100 100 000 - 0
199 UDMA_CRC_Error_Count -OSRCK 200 200 000 - 0
240 Head_Flying_Hours ------ 100 100 000 - 529 (206 38 0)
241 Total_LBAs_Written ------ 100 253 000 - 19648189091
242 Total_LBAs_Read ------ 100 253 000 - 9322473897
||||||_ K auto-keep
|||||__ C event count
||||___ R error rate
|||____ S speed/performance
||_____ O updated online
|______ P prefailure warning
General Purpose Log Directory Version 1
SMART Log Directory Version 1 [multi-sector log support]
Address Access R/W Size Description
0x00 GPL,SL R/O 1 Log Directory
0x01 SL R/O 1 Summary SMART error log
0x02 SL R/O 5 Comprehensive SMART error log
0x03 GPL R/O 5 Ext. Comprehensive SMART error log
0x04 GPL R/O 256 Device Statistics log
0x04 SL R/O 8 Device Statistics log
0x06 SL R/O 1 SMART self-test log
0x07 GPL R/O 1 Extended self-test log
0x08 GPL R/O 2 Power Conditions log
0x09 SL R/W 1 Selective self-test log
0x0a GPL R/W 8 Device Statistics Notification
0x0c GPL R/O 2048 Pending Defects log
0x10 GPL R/O 1 NCQ Command Error log
0x11 GPL R/O 1 SATA Phy Event Counters log
0x13 GPL R/O 1 SATA NCQ Send and Receive log
0x21 GPL R/O 1 Write stream error log
0x22 GPL R/O 1 Read stream error log
0x24 GPL R/O 768 Current Device Internal Status Data log
0x2f GPL R/O 1 Set Sector Configuration
0x30 GPL,SL R/O 9 IDENTIFY DEVICE data log
0x80-0x9f GPL,SL R/W 16 Host vendor specific log
0xa1 GPL,SL VS 160 Device vendor specific log
0xa2 GPL VS 16320 Device vendor specific log
0xa4 GPL,SL VS 160 Device vendor specific log
0xa6 GPL VS 192 Device vendor specific log
0xa8-0xa9 GPL,SL VS 136 Device vendor specific log
0xab GPL VS 1 Device vendor specific log
0xad GPL VS 16 Device vendor specific log
0xb1 GPL,SL VS 160 Device vendor specific log
0xb6 GPL VS 1920 Device vendor specific log
0xbe-0xbf GPL VS 65535 Device vendor specific log
0xc1 GPL,SL VS 8 Device vendor specific log
0xc3 GPL,SL VS 24 Device vendor specific log
0xc6 GPL VS 5184 Device vendor specific log
0xc7 GPL,SL VS 8 Device vendor specific log
0xc9 GPL,SL VS 8 Device vendor specific log
0xca GPL,SL VS 16 Device vendor specific log
0xcd GPL,SL VS 1 Device vendor specific log
0xce GPL VS 1 Device vendor specific log
0xcf GPL VS 512 Device vendor specific log
0xd1 GPL VS 656 Device vendor specific log
0xd2 GPL VS 10256 Device vendor specific log
0xd4 GPL VS 2048 Device vendor specific log
0xda GPL,SL VS 1 Device vendor specific log
0xe0 GPL,SL R/W 1 SCT Command/Status
0xe1 GPL,SL R/W 1 SCT Data Transfer
SMART Extended Comprehensive Error Log Version: 1 (5 sectors)
No Errors Logged
SMART Extended Self-test Log Version: 1 (1 sectors)
Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error
# 1 Extended offline Completed without error 00% 1563 -
# 2 Short offline Completed without error 00% 1551 -
# 3 Short offline Completed without error 00% 1462 -
SMART Selective self-test log data structure revision number 1
SPAN MIN_LBA MAX_LBA CURRENT_TEST_STATUS
1 0 0 Not_testing
2 0 0 Not_testing
3 0 0 Not_testing
4 0 0 Not_testing
5 0 0 Not_testing
Selective self-test flags (0x0):
After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.
SCT Status Version: 3
SCT Version (vendor specific): 522 (0x020a)
Device State: Active (0)
Current Temperature: 37 Celsius
Power Cycle Min/Max Temperature: 26/45 Celsius
Lifetime Min/Max Temperature: 23/46 Celsius
Under/Over Temperature Limit Count: 0/14
SMART Status: 0xc24f (PASSED)
Vendor specific:
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 03 00 00 00 00 00 00 00 00 00 00 00
SCT Temperature History Version: 2
Temperature Sampling Period: 4 minutes
Temperature Logging Interval: 59 minutes
Min/Max recommended Temperature: 10/40 Celsius
Min/Max Temperature Limit: 5/60 Celsius
Temperature History Size (Index): 128 (8)
Index Estimated Time Temperature Celsius
9 2025-12-29 18:39 36 *****************
10 2025-12-29 19:38 ? -
11 2025-12-29 20:37 36 *****************
12 2025-12-29 21:36 36 *****************
13 2025-12-29 22:35 35 ****************
... ..( 4 skipped). .. ****************
18 2025-12-30 03:30 35 ****************
19 2025-12-30 04:29 34 ***************
... ..( 2 skipped). .. ***************
22 2025-12-30 07:26 34 ***************
23 2025-12-30 08:25 33 **************
24 2025-12-30 09:24 33 **************
25 2025-12-30 10:23 33 **************
26 2025-12-30 11:22 32 *************
... ..( 3 skipped). .. *************
30 2025-12-30 15:18 32 *************
31 2025-12-30 16:17 33 **************
32 2025-12-30 17:16 33 **************
33 2025-12-30 18:15 32 *************
... ..( 10 skipped). .. *************
44 2025-12-31 05:04 32 *************
45 2025-12-31 06:03 31 ************
... ..( 5 skipped). .. ************
51 2025-12-31 11:57 31 ************
52 2025-12-31 12:56 30 ***********
... ..( 8 skipped). .. ***********
61 2025-12-31 21:47 30 ***********
62 2025-12-31 22:46 31 ************
... ..( 3 skipped). .. ************
66 2026-01-01 02:42 31 ************
67 2026-01-01 03:41 30 ***********
... ..( 10 skipped). .. ***********
78 2026-01-01 14:30 30 ***********
79 2026-01-01 15:29 29 **********
80 2026-01-01 16:28 29 **********
81 2026-01-01 17:27 29 **********
82 2026-01-01 18:26 30 ***********
83 2026-01-01 19:25 29 **********
84 2026-01-01 20:24 29 **********
85 2026-01-01 21:23 29 **********
86 2026-01-01 22:22 30 ***********
87 2026-01-01 23:21 30 ***********
88 2026-01-02 00:20 32 *************
89 2026-01-02 01:19 33 **************
90 2026-01-02 02:18 33 **************
91 2026-01-02 03:17 33 **************
92 2026-01-02 04:16 32 *************
93 2026-01-02 05:15 31 ************
94 2026-01-02 06:14 ? -
95 2026-01-02 07:13 30 ***********
96 2026-01-02 08:12 ? -
97 2026-01-02 09:11 30 ***********
98 2026-01-02 10:10 ? -
99 2026-01-02 11:09 30 ***********
100 2026-01-02 12:08 ? -
101 2026-01-02 13:07 30 ***********
102 2026-01-02 14:06 ? -
103 2026-01-02 15:05 30 ***********
104 2026-01-02 16:04 ? -
105 2026-01-02 17:03 30 ***********
106 2026-01-02 18:02 ? -
107 2026-01-02 19:01 31 ************
108 2026-01-02 20:00 ? -
109 2026-01-02 20:59 31 ************
110 2026-01-02 21:58 ? -
111 2026-01-02 22:57 26 *******
112 2026-01-02 23:56 38 *******************
113 2026-01-03 00:55 36 *****************
114 2026-01-03 01:54 34 ***************
115 2026-01-03 02:53 33 **************
... ..( 4 skipped). .. **************
120 2026-01-03 07:48 33 **************
121 2026-01-03 08:47 37 ******************
122 2026-01-03 09:46 42 ***********************
123 2026-01-03 10:45 43 ************************
124 2026-01-03 11:44 42 ***********************
125 2026-01-03 12:43 43 ************************
126 2026-01-03 13:42 44 *************************
127 2026-01-03 14:41 45 **************************
0 2026-01-03 15:40 43 ************************
1 2026-01-03 16:39 43 ************************
2 2026-01-03 17:38 42 ***********************
... ..( 2 skipped). .. ***********************
5 2026-01-03 20:35 42 ***********************
6 2026-01-03 21:34 41 **********************
7 2026-01-03 22:33 41 **********************
8 2026-01-03 23:32 38 *******************
SCT Error Recovery Control:
Read: 70 (7.0 seconds)
Write: 70 (7.0 seconds)
Device Statistics (GP Log 0x04)
Page Offset Size Value Flags Description
0x01 ===== = = === == General Statistics (rev 1) ==
0x01 0x008 4 237 --- Lifetime Power-On Resets
0x01 0x010 4 1564 --- Power-on Hours
0x01 0x018 6 19393406971 --- Logical Sectors Written
0x01 0x020 6 40248649 --- Number of Write Commands
0x01 0x028 6 9269776944 --- Logical Sectors Read
0x01 0x030 6 154066717 --- Number of Read Commands
0x01 0x038 6 - --- Date and Time TimeStamp
0x03 ===== = = === == Rotating Media Statistics (rev 1) ==
0x03 0x008 4 1215 --- Spindle Motor Power-on Hours
0x03 0x010 4 528 --- Head Flying Hours
0x03 0x018 4 1965 --- Head Load Events
0x03 0x020 4 0 --- Number of Reallocated Logical Sectors
0x03 0x028 4 0 --- Read Recovery Attempts
0x03 0x030 4 0 --- Number of Mechanical Start Failures
0x03 0x038 4 0 --- Number of Realloc. Candidate Logical Sectors
0x03 0x040 4 229 --- Number of High Priority Unload Events
0x04 ===== = = === == General Errors Statistics (rev 1) ==
0x04 0x008 4 0 --- Number of Reported Uncorrectable Errors
0x04 0x010 4 0 --- Resets Between Cmd Acceptance and Completion
0x04 0x018 4 0 -D- Physical Element Status Changed
0x05 ===== = = === == Temperature Statistics (rev 1) ==
0x05 0x008 1 37 --- Current Temperature
0x05 0x010 1 35 --- Average Short Term Temperature
0x05 0x018 1 34 --- Average Long Term Temperature
0x05 0x020 1 46 --- Highest Temperature
0x05 0x028 1 27 --- Lowest Temperature
0x05 0x030 1 43 --- Highest Average Short Term Temperature
0x05 0x038 1 30 --- Lowest Average Short Term Temperature
0x05 0x040 1 34 --- Highest Average Long Term Temperature
0x05 0x048 1 34 --- Lowest Average Long Term Temperature
0x05 0x050 4 0 --- Time in Over-Temperature
0x05 0x058 1 60 --- Specified Maximum Operating Temperature
0x05 0x060 4 0 --- Time in Under-Temperature
0x05 0x068 1 5 --- Specified Minimum Operating Temperature
0x06 ===== = = === == Transport Statistics (rev 1) ==
0x06 0x008 4 41 --- Number of Hardware Resets
0x06 0x010 4 8 --- Number of ASR Events
0x06 0x018 4 0 --- Number of Interface CRC Errors
0xff ===== = = === == Vendor Specific Statistics (rev 1) ==
0xff 0x010 7 0 --- Vendor Specific
0xff 0x018 7 0 --- Vendor Specific
|||_ C monitored condition met
||__ D supports DSN
|___ N normalized value
Pending Defects log (GP Log 0x0c)
No Defects Logged
SATA Phy Event Counters (GP Log 0x11)
ID Size Value Description
0x000a 2 2 Device-to-host register FISes sent due to a COMRESET
0x0001 2 0 Command failed due to ICRC error
0x0003 2 0 R_ERR response for device-to-host data FIS
0x0004 2 0 R_ERR response for host-to-device data FIS
0x0006 2 0 R_ERR response for device-to-host non-data FIS
0x0007 2 0 R_ERR response for host-to-device non-data FIS
Seagate FARM log (GP Log 0xa6) supported [try: -l farm]
```
- Execution finished, nothing else to do. The disk remains in the mirror.
- Other notes
- I labeled the two disks by hand as AGAPITO1 and AGAPITO2, but I never noted their serial numbers. Silly me. This is the relation:
- AGAPITO1 is ata-ST4000NT001-3M2101_WX11TN0Z.
- AGAPITO2 is ata-ST4000NT001-3M2101_WX11TN2P.
## Side quests
### Using and understanding dmesg
#### Generalities
The Linux Kernel writes into the kernel ring buffer. This is an in-memory log where the kernel writes messages. The `dmesg` command reads from it. This log contains relatively low-level info from the kernel, including hardware related operations.
This is an in-memory structure because it starts very early in the boot process, right after the bootloader. Hence, information is held in-memory before the disk file-systems are available and `syslog` can persist logs.
Because of the in-memory nature, info on hardware failures is available in the kernel ring buffer before appearing in other persisted logs.
Good keywords to `grep` the output of `dmesg` to find hard drive related issues include:
- ata
- sata
- ahci
- link
- COMRESET
- PHY
#### Specific examples
Some examples of telling log lines:
```
ata4: hard resetting link
ata4: SATA link down (SStatus 0 SControl 300)
ata4: link is slow to respond, please be patient (ready=0)
ata4: found unknown device (class 0)
```
The disk is connecting and disconnecting, or appears slow, or doesn't display info for not being properly connected (`unknown device`).
```
ata4: limiting SATA link speed to 3.0 Gbps
ata4: limiting SATA link speed to 1.5 Gbps
```
Speed downgrades.
```
I/O error, dev sdb, sector 5414318144 op 0x0:(READ)
I/O error, dev sdb, sector 7814018064 op 0x0:(READ)
```
Failures of read attempts.
#### Why is it called dmesg?
`dmesg` stands for "diagnostic message".
#### What about persistence of logs?
Once userspace is available, `systemd-journald` reads messages. The kernel exposes the messages in `/dev/kmsg` for streaming. Those are copied into the in-memory journal. Then they get flushed to disk according to journald own policies and events.
Kernel messages have log levels (EMERG, ALERT, CRIT, ...). The userspace processes decide which levels deserve to hit disk persistence and what's simply left in the ring buffer.
### Why do SATA drives get mentioned as SCIS drives in Kernel log messages?
SCIS is the protocol used by SAS drives.
The Linux Kernel uses the SCIS protocol as an emulated middleware layer between the actual ATA protocol used by the hard drive firmware.
### Understanding smartctl
#### Naming and maintenance
Stands for Self-monitoring, Analysis, and Reporting Technology Control.
It's maintained by three randos, classic xkcd fragile software supply chain meme.
#### About the commands
`smartctl -t short /dev/sdx` prompts the drive to run a self-test. It's a very basic check that doesn't actually fully examine the disk. Having a failure in the short test basically guarantees that the disk is toast. It checks:
- That CPU, RAM, etc work.
- That the onboard microcode execution works fine.
- It reads a small subset of the disk and verifies that it's readable.
- It moves the mechanical parts to check they work.
By contrast, the longcheck (`smartctl -t long /dev/sdx`) actually reads every block on the disk to verify it can be read correctly.
`smartctl -l selftest /dev/sdx` just reads the result of the selftests.
#### On SATA vs SCSI (SAS) drives
SAS drives are enterprise drives with much more advanced reporting features and a different approach to transparency.
SATA drives run the vendor firmware, which keeps most details private and doesn't share them with the Linux. The drive itself decies when to report failues back to smartmontools.
SAS drives, on the other hand, provides more transparency, informs of failures earlier, and doesn't try to simplify and "hide" issues.
In the context of ZFS, SCSI helps the ZFS runtime realise faster that the disk is hiccup-y and make the call of marking it degraded and relying on alternative disks. SATA drives do not "confess" issues that fast, so the ZFS runtime keeps trying to use them and facing issues, which makes reads/writes fail and performance go to shit until finally ZFS decides to mark it degraded.
SAS drives don't fit on SATA ports: to plug them into a regular motherboard, you need a SAS controller
## Open questions
- How can I automate the monitoring of the ZFS pool or the disks to avoid this issue happening silently again?
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