Hi, I'm opening this thread to ask about a problem I encountered.

My ZFS pool (raidz1 with seven 18TB disks) was originally from patch ~6.12, and if I remember correctly, I created it following the instructions in one of SpaceInvader's videos.

One of the disks started showing read/pending sector errors, so I decided to replace it.

At the time, I didn't think about the fact that I had an old pool that hadn't been created via the GUI (I honestly didn't even remember).

Anyway, I shut down the array, powered off the server, and replaced the defective disk (2JH2S5PB). Once powered back up, I simply performed the swap via the GUI as shown in the image.

From that point on, after starting the array, the pool was imported in a DEGRADED state, but from the logs it appears that emhttpd/Unraid then initiated a replace against a member that was ONLINE, rather than against the missing device.

Furthermost, a few seconds later, the logs also show a GPT/wipefs write to another disk in the same pool that ZFS had just reported as ONLINE.

Unfortunately, I read later in some posts that "potential issues" are mentioned when using the GUI with ZFS pools created before 7.0 using cli, so I don't know if what happened falls under this category.

I should point out right away that the data was recovered and the pool was subsequently recreated, so I'm not asking for help with data recovery. I'd just like to understand if the following chain of events is "expected behavior" with a legacy/imported pool, or if it's something that deserves attention/reporting.

I didn't save the diagnostic report and can only attach the most recent one from the machine (which I've now recreated to RAIDZ2 for peace of mind). :(

However, I do have the syslog and some other files from those moments during the disk replacement.

This is what the GUI showed moments before selecting the replacement disk and pressing start.

Jun 2 14:33:56 Serverini emhttpd: pool: zfs
Jun 2 14:33:56 Serverini emhttpd: state: DEGRADED
Jun 2 14:33:56 Serverini emhttpd: config:
Jun 2 14:33:56 Serverini emhttpd: #011NAME STATE READ WRITE CKSUM
Jun 2 14:33:56 Serverini emhttpd: #011zfs DEGRADED 0 0 0
Jun 2 14:33:56 Serverini emhttpd: #011 raidz1-0 DEGRADED 0 0 0
Jun 2 14:33:56 Serverini emhttpd: #011 4298119360728290295 UNAVAIL 0 0 0 was /dev/sdh1
Jun 2 14:33:56 Serverini emhttpd: #011 /dev/sdg1 ONLINE 0 0 0
Jun 2 14:33:56 Serverini emhttpd: #011 /dev/sdf1 ONLINE 0 0 0
Jun 2 14:33:56 Serverini emhttpd: #011 /dev/sde1 ONLINE 0 0 0
Jun 2 14:33:56 Serverini emhttpd: #011 /dev/sdb1 ONLINE 0 0 0
Jun 2 14:33:56 Serverini emhttpd: #011 /dev/sda1 ONLINE 0 0 0
Jun 2 14:33:56 Serverini emhttpd: #011 /dev/sdd1 ONLINE 0 0 0
Jun 2 14:33:56 Serverini emhttpd: errors: No known data errors

root@Serverini:~# zpool status -v zfs
pool: zfs
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 Tue Jun 2 14:34:02 2026
603G / 72.3T scanned at 11.8G/s, 0B / 72.3T issued
0B resilvered, 0.00% done, no estimated completion time
config:
NAME STATE READ WRITE CKSUM
zfs DEGRADED 0 0 0
raidz1-0 DEGRADED 0 0 0
4298119360728290295 UNAVAIL 0 0 0 was /dev/sdh1
replacing-1 ONLINE 0 0 0
sdg ONLINE 0 0 0
sdh1 ONLINE 0 0 0
sdf ONLINE 0 0 0
sde ONLINE 0 0 0
sdb ONLINE 0 0 0
sda ONLINE 0 0 0
sdd ONLINE 0 0 0
errors: No known data errors

pool: zfs
id: 9756493019432944573
state: FAULTED
status: One or more devices contains corrupted data.
action: The pool cannot be imported due to damaged devices or data.
The pool may be active on another system, but can be imported using
the '-f' flag.
config:
zfs FAULTED corrupted data
raidz1-0 DEGRADED
sdh ONLINE
replacing-1 DEGRADED
sdg ONLINE
sdh1 FAULTED corrupted data
sdf ONLINE
ata-WDC_WUH721818ALE6L4_5DH06YTR ONLINE
ata-WUH721818ALE6L4_3FHEJURT ONLINE
sda UNAVAIL invalid label
ata-WUH721818ALE6L4_5DGYPG6J ONLINE

I used AI support to check the logs during those moments, so if I've written anything stupid, I apologize in advance (I'm no expert on ZFS at all). :D

syslog_before_reboot.txt by-id.txt serverini-diagnostics-20260606-0937.zip

Edited June 6Jun 6 by exus

7.3.0 has a bug replacing a device from a RAIDZ pools, but it should have been easily recoverable if you didn't do anything else.

Since the pool was reformatted, there is not much to do now, but make sure you update to 7.3.1