One of the HDDs in my software RAID 1 on a dedicated server is damaged. The customer support is slow to respond. I would like to transfer all data I need to another server, but file access is unbelievable slow. How can I disable the raid, so I can mount the healthy HHD and just read the files? My root and home are both on a separate partition on the RAID 1. /dev/sda is damaged, /dev/sdb is healthy.


mount output:

/dev/root on / type ext4 (rw,relatime,errors=remount-ro,data=ordered)
devtmpfs on /dev type devtmpfs (rw,relatime,size=8162340k,nr_inodes=2040585,mode=755)
tmpfs on /run type tmpfs (rw,nosuid,noexec,relatime,size=1632560k,mode=755)
tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,noexec,relatime,size=3474420k)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620)
/dev/md2 on /home type ext4 (rw,relatime,data=ordered)

cat /proc/mdstat output:

Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] [multipath] [faulty]`

md1 : active raid1 sdb1[1]
      30718912 blocks [2/1] [_U]

md2 : active raid1 sdb2[1] sda2[0]
      945514432 blocks [2/2] [UU]
      [=>...................]  resync =  7.1% (67819328/945514432) finish=5804590.2min speed=2K/sec

With md software RAID, which you've indicated you have, you can usually just unmount the RAID device, and mount the healthy member, eg with /dev/md1, made up of /dev/sda5 and /dev/sdb5, the latter being faulty, and the whole thing mounted on /data, you could do:

umount /data 
mount /dev/sda5 /data

However, with the tiny amount of information you've given us, I suspect that it may be your root partition, or some other part of the OS that can't easily be unmounted in production. If you could update your question with the output of mount and cat /proc/mdstat, and perhaps the name of the partition in question, we might be better able to shed more light.

Edit: I see you're in the middle of live RAID reconstruct. No wonder the discs are slow, for now. This should pass, when reconstruction completes. If it doesn't, fail the bad partitions out of the RAID with e.g. mdadm md2 -f /dev/sda2, then things should speed up again.

Your longer-term strategy should be to replace the bad disc, but how to do that is way beyond the scope of a Server Fault question.

  • Thanks for your help. You're right, the raid includes my root partition. I attached the output of mount and cat /proc/mdstat to the original question. – JaVaEs Oct 7 '14 at 12:30

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