Few weeks ago I set up a home server using Ubuntu Server. In addition to a small SSD drive, it has a pair of 3TB WD Reds which are supposed to be in a mirrored RAID configuration. I followed this tutorial and everything seemed to work out fine. After mounting the resulting md0 device, I got a 3TB drive as expected. I copied about 2TB of data there and left it as it was. Now a week or two later, all the data seems to be gone and I can't figure out what happened. I am primarily a Windows user, so a lot of this stuff is quite confusing to me.

mdstat suggests the RAID array is working

cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sdc[1] sdb[0]
      2930135488 blocks super 1.2 [2/2] [UU]
      bitmap: 0/22 pages [0KB], 65536KB chunk

df is super confusing to me (ls /mnt/md0 returns empty)

df /mnt/md0
Filesystem                         1K-blocks    Used Available Use% Mounted on
/dev/mapper/matej--server--vg-root  98049684 7840560  85205452   9% /

mdadm detail also suggests everything is okay

 sudo mdadm --detail /dev/md0
        Version : 1.2
  Creation Time : Sun Oct  2 00:06:19 2016
     Raid Level : raid1
     Array Size : 2930135488 (2794.40 GiB 3000.46 GB)
  Used Dev Size : 2930135488 (2794.40 GiB 3000.46 GB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Fri Oct  7 02:01:48 2016
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           Name : matej-server:0  (local to host matej-server)
           UUID : 60012283:78eb25cb:8868aede:f515fbef
         Events : 6754

    Number   Major   Minor   RaidDevice State
       0       8       16        0      active sync   /dev/sdb
       1       8       32        1      active sync   /dev/sdc

Did I make some error configuring the RAID or did something go horribly wrong afterwards?

  • 2
    So... you forgot to mount it? file -s /dev/md*, lsblk, ... in the simplest case, mount /dev/md0 /mnt/md0 – frostschutz Oct 22 '16 at 20:08
  • As frostschutz points out, likely not mounted. Did you forget to add into /etc/fstab, so that it mounted on boot, and have since rebooted ? – steve Oct 22 '16 at 20:55

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