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gjblackford 02-05-2013 02:13 AM

Software Raid

I have been testing out how to setup Software Raid before doing it for real on a new PC. So far I have worked out how to setup the RAID, but after looking on the internet and playing have not yet worked out how to identify the state of the RAID (e.g. is it Synced across both devices etc...)

I know to get info about the Raid I can do the following

cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md0 : active raid1 sdb1[1] sda1[0]
      10476416 blocks super 1.2 [2/2] [UU]

unused devices: <none>


sudo mdadm -D /dev/md0
        Version : 1.2
  Creation Time : Mon Feb  4 19:53:19 2013
    Raid Level : raid1
    Array Size : 10476416 (9.99 GiB 10.73 GB)
  Used Dev Size : 10476416 (9.99 GiB 10.73 GB)
  Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

    Update Time : Mon Feb  4 21:35:23 2013
          State : active
Active Devices : 2
Working Devices : 2
Failed Devices : 0
  Spare Devices : 0

          Name : ubuntu:0  (local to host ubuntu)
          UUID : 87e5f322:fa51c75a:be1078a5:f9850e8c
        Events : 58

    Number  Major  Minor  RaidDevice State
      0      8        1        0      active sync  /dev/sda1
      1      8      17        1      active sync  /dev/sdb1

Is anyone able to point me to a good resource on understanding this or explain how I can know if the RAID is synced across both disks.


acid_kewpie 02-05-2013 03:59 AM

the state of "active sync" from mdadm and the "U" (for "up" afaik)in mdstat show that they are synced.

gjblackford 02-05-2013 08:15 AM

Thanks, you don't know anywhere I can find out details of the States and what each means, the man pages and Wiki only seem to have info on how to setup, delete RAID configs etc..

So far from looking at screenshots I have seen clean, active & degraded, but I would imagine there are more.

jefro 02-05-2013 03:43 PM

Some more info here that may or may not help.

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