C7 And Mdadm

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A user’s system had a hard drive failure over the weekend. Linux RAID 6. I
identified the drive, brought the system down (8 drives, and I didn’t know the s/n of the bad one. why it was there in the box, rather than where I
started looking…) Brought it up, RAID not working. I finally found that I had to do an mdadm –stop /dev/md0, then I could do an assemble, then I
could add the new drive.

But: it’s now cat /proc/mdstat Personalities : [raid6] [raid5] [raid4]
md0 : active (auto-read-only) raid5 sdg1[8](S) sdh1[7] sdf1[4] sde1[3]
sdd1[2] sdc1[1]
23441313792 blocks super 1.2 level 5, 512k chunk, algorithm 2 [7/5]
[_UUUU_U]
bitmap: 0/30 pages [0KB], 65536KB chunk

unused devices:

and I can’t mount it (it’s xfs, btw). *Should* I make it readwrite, or is there something else I should do?

mark

2 thoughts on - C7 And Mdadm

  • Am 22.01.2019 um 23:26 schrieb mark:
    [ … ]

    I see a RAID 5 with 2 elements missing from the array. That would mean data is lost.

    Alexander

  • That doesn’t look like RAID 6.  That looks like RAID 5 with a hot spare.  There appear to be two drives missing.  If you can locate one of those two drives and add it to the array, you should be able to start it and mount the filesystem.   Otherwise you’ll have to restore backups.

    The drive that failed this weekend may work well enough to add it to the array temporarily if you need to refresh your backups.