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Old 09-13-2007, 07:42 PM   #1
pnotequalsnp
LQ Newbie
 
Registered: Sep 2007
Posts: 4

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Raid 5 Disappears


I have (*ahem had) a raid 5 setup with four 500GB SATA hard drives for storage. I rebooted the machine and it did not mount the raid drive.

Short Version: mdstat says I only have 2/4 working drives, but it looks like I have 3/4 (at least) working drives.

Long Version:
So I checked mdastat
Code:
>sudo cat /proc/mdstat 
Personalities : [raid6] [raid5] [raid4] 
md0 : inactive sdc1[1](S) sdd1[2](S)
      976767872 blocks
       
unused devices: <none>
and that was odd so I tried to use mdadm
Code:
>sudo mdadm -As /dev/md0
mdadm: /dev/md0 assembled from 2 drives - not enough to start the array.
Then I thought that 2(!) drives out of the 4 failed, no way since I just bought them and it is been working for about 4 days now. So then I used sfdisk for each of the four drives
Code:
>sudo sfdisk -l /dev/sdb

Disk /dev/sdb: 60801 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sdb1          0       -       0          0    0  Empty
/dev/sdb2          0       -       0          0    0  Empty
/dev/sdb3          0       -       0          0    0  Empty
/dev/sdb4          0       -       0          0    0  Empty

>sudo sfdisk -l /dev/sdc

Disk /dev/sdc: 60801 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sdc1          0+  60800   60801- 488384001   83  Linux
/dev/sdc2          0       -       0          0    0  Empty
/dev/sdc3          0       -       0          0    0  Empty
/dev/sdc4          0       -       0          0    0  Empty

>sudo sfdisk -l /dev/sdd

Disk /dev/sdd: 60801 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sdd1          0+  60800   60801- 488384001   83  Linux
/dev/sdd2          0       -       0          0    0  Empty
/dev/sdd3          0       -       0          0    0  Empty
/dev/sdd4          0       -       0          0    0  Empty

>sudo sfdisk -l /dev/sde

Disk /dev/sde: 60801 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls    #blocks   Id  System
/dev/sde1          0+  60800   60801- 488384001   83  Linux
/dev/sde2          0       -       0          0    0  Empty
/dev/sde3          0       -       0          0    0  Empty
/dev/sde4          0       -       0          0    0  Empty
and we see that there is something wrong with /dev/sdb (where did you go?).

But when I try to start up the device (because it looks like I have 3 working) I get the same error that there are only 2 drives available.

So then I tried to use mdadm again and got:
Code:
>sudo mdadm -E /dev/sdb1
mdadm: cannot open /dev/sdb1: No such file or directory
nhomer@ubuntu-desktop:~$ sudo mdadm -E /dev/sdc1
/dev/sdc1:
          Magic : a92b4efc
        Version : 00.90.00
           UUID : a5dcb6ff:0d931c7f:bb855af7:201184b4 (local to host ubuntu-desktop)
  Creation Time : Sun Sep  9 22:14:31 2007
     Raid Level : raid5
    Device Size : 488383936 (465.76 GiB 500.11 GB)
     Array Size : 1465151808 (1397.28 GiB 1500.32 GB)
   Raid Devices : 4
  Total Devices : 3
Preferred Minor : 0

    Update Time : Thu Sep 13 01:43:04 2007
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0
       Checksum : e31dd26f - correct
         Events : 0.28452

         Layout : left-symmetric
     Chunk Size : 64K

      Number   Major   Minor   RaidDevice State
this     1       8       33        1      active sync   /dev/sdc1

   0     0       0        0        0      removed
   1     1       8       33        1      active sync   /dev/sdc1
   2     2       8       49        2      active sync   /dev/sdd1
   3     3       8       65        3      active sync   /dev/sde1

>sudo mdadm -E /dev/sdd1
/dev/sdd1:
          Magic : a92b4efc
        Version : 00.90.00
           UUID : a5dcb6ff:0d931c7f:bb855af7:201184b4 (local to host ubuntu-desktop)
  Creation Time : Sun Sep  9 22:14:31 2007
     Raid Level : raid5
    Device Size : 488383936 (465.76 GiB 500.11 GB)
     Array Size : 1465151808 (1397.28 GiB 1500.32 GB)
   Raid Devices : 4
  Total Devices : 3
Preferred Minor : 0

    Update Time : Thu Sep 13 01:43:04 2007
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0
       Checksum : e31dd281 - correct
         Events : 0.28452

         Layout : left-symmetric
     Chunk Size : 64K

      Number   Major   Minor   RaidDevice State
this     2       8       49        2      active sync   /dev/sdd1

   0     0       0        0        0      removed
   1     1       8       33        1      active sync   /dev/sdc1
   2     2       8       49        2      active sync   /dev/sdd1
   3     3       8       65        3      active sync   /dev/sde1

>sudo mdadm -E /dev/sde1
/dev/sde1:
          Magic : a92b4efc
        Version : 00.90.00
           UUID : a5dcb6ff:0d931c7f:4bc81c71:77d10fa7
  Creation Time : Sun Sep  9 22:14:31 2007
     Raid Level : raid5
    Device Size : 488383936 (465.76 GiB 500.11 GB)
     Array Size : 1465151808 (1397.28 GiB 1500.32 GB)
   Raid Devices : 4
  Total Devices : 3
Preferred Minor : 0

    Update Time : Thu Sep 13 01:43:04 2007
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0
       Checksum : cb201f00 - correct
         Events : 0.28452

         Layout : left-symmetric
     Chunk Size : 64K

      Number   Major   Minor   RaidDevice State
this     3       8       65        3      active sync   /dev/sde1

   0     0       0        0        0      removed
   1     1       8       33        1      active sync   /dev/sdc1
   2     2       8       49        2      active sync   /dev/sdd1
   3     3       8       65        3      active sync   /dev/sde1
Basically at this point I am open to any suggestions (I don't want to have to reload ~1 TB of data please). How do I get this working and am I even on the right track?
 
Old 10-11-2007, 06:57 PM   #2
theyollom
LQ Newbie
 
Registered: Oct 2007
Posts: 1

Rep: Reputation: 0
Unhappy Did you have an answer or find a solution ?

Could you advise if you have found a solution to this problem. My own setup went this evening but all drives report OK. Hoever MDADM says can only find 2 drives - not enough - but all four dries are there !

ANY help would be appreciated
Thanks
 
  


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