But what is that command? And how do you know which disk has gone bad?
I am sure I can get an answer from Google / Claude / ChatGPT, but a guide is incomplete without it - and the failure report should be active like a beep or flashing hardware light - I typically log into my NAS only a few times a year. A motd or other banner isn’t sufficient.
I used to look after storage arrays for VFX places.
everytime I saw lvm I inwardly sighed. The docs were terrible, almost as bad as MDADM. snapshots were for a long time unrecoverable. You'd then have to work out what pattern of LV you had, was it a suprise raid0? or a misaligned raid1?
zfs is a night and day compared to LVM/mdadm, two tools, rich help, the man pages are reasonably good, and once you understand zfs vs zpool, you're usually good to go.
https://openzfs.github.io/openzfs-docs/man/master/8/zpool-re...
ZFS got this right. MDADM on ext4 somehow did not.
EDIT: ext4 on MDADM.
How ZFS gets this right: zfs(8) on zpool(8). So, basically, ext4 and mdadm can talk to each other.
schedule a zpool scrub every month, send an email if it finds errors. zpool status will show the errored drive. zpool replace will initiate the drive replacement.