Storage / Stage 5 of 12

RAID 1: a disk has failed

Not running Starting usually ~20 s

Step 8 of 8 · summary · 1 min

Summary

A mirror (RAID 1) keeps a full copy on every disk and works while at least one of them is alive.
/proc/mdstat and mdadm --detail show the failed disk (F) and the degraded state.
The failed disk is removed with mdadm --remove and the new one added with --add; there is no margin until the rebuild ends.
An ARRAY line in mdadm.conf pins a name to the array — one line per array, and on a server update-initramfs -u after the edit.
At the start of the lesson the files could be read because the array ran on the remaining disk, loop0: [2/1] [U_].

Ubuntu 24.04