Another day for me with server trouble. On my server I use the Freebsd gmirror (software raid) with mirrored disks. It has worked perfectly for the last couple of years, however today I found out that my gmirror raid1 was degraded. The ”gmirror list” command told me that one of my disks was missing in the raid. The error message in /var/log/messages was the somewhat strange ”GEOM_MIRROR: Component ad2 (device gm0) broken, skipping”. Is my disk (ad2) bad or what? Why is gm0 broken? The disk is actually running and seems to be okey.
I found a solution for the problem. If you remove the ”missing disk” from the raid and then insert it again, then the raid is rebuilt. For me the raid seems to be working again.
gmirror deactivate -v gm0 ad2
gmirror forget -v gm0
gmirror insert -v gm0 ad2