Recovering a Linux RAID disk
I had a server with a flaky drive sneak up on me today. After the server took a break (requiring a hard reboot), I found this in the dmesg report:
md: md3: raid array is not clean — starting background reconstruction
md: RAID level 1 does not need chunksize! Continuing anyway.
md3: max total readahead window set to 124k
md3: 1 data-disks, max readahead per data-disk: 124k
raid1: device sda3 operational as mirror 0
raid1: md3, not all disks are operational — trying to recover array
raid1: raid set md3 active with 1 out of 2 mirrors
md3: no spare disk to reconstruct array! — continuing in degraded mode
Naturally, this concerned me. Especially the part about “continuing in degraded mode”.
The solution? Well, we’ll know for sure soon. Hopefully it won’t require a new hard drive. But this nice little tutorial gave me just the detail I needed to check on status and get headed down the right path: