Re: Strange behaviour on "toy array"

Patrik Jonsson <patrik@xxxxxxxxxxx> · Sun, 15 May 2005 13:55:13 -0700

David Greaves wrote:

I think you'd need to post the commands you used and the results of 
things like mdadm --detail and cat /proc/mdstat

also kernel version, mdadm version etc.

That way we can ensure you really did fail the right drives etc etc.

Right now it could be anything from (allowed!) user error to a weird ppc

thing...

sure thing:

[root@localhost junk]# uname -a

Linux localhost.localdomain 2.6.9-prep #1 Tue Apr 19 16:00:33 PDT 2005 
ppc ppc ppc GNU/Linux

[root@localhost junk]# mdadm --version

mdadm - v1.6.0 - 4 June 2004

now I do (loop1-5 are files):

losetup /dev/loop0 loop1

losetup /dev/loop1 loop2

losetup /dev/loop2 loop3

losetup /dev/loop3 loop4

losetup /dev/loop4 loop5

mdadm --create /dev/md0 -l 5 -n 5 /dev/loop0 /dev/loop1 /dev/loop2 
/dev/loop3 /dev/loop4

mkfs.ext3 /dev/md0

mount -t ext3 /dev/md0 junk

at this point, mdadm shows:
[root@localhost junk]# mdadm --detail /dev/md0
/dev/md0:
       Version : 00.90.01
 Creation Time : Sun May 15 13:41:24 2005
    Raid Level : raid5
    Array Size : 3840
   Device Size : 960
  Raid Devices : 5
 Total Devices : 5
Preferred Minor : 0
   Persistence : Superblock is persistent

   Update Time : Sun May 15 13:45:34 2005
         State : clean
Active Devices : 5
Working Devices : 5
Failed Devices : 0
 Spare Devices : 0

        Layout : left-symmetric
    Chunk Size : 64K

   Number   Major   Minor   RaidDevice State
      0       7        0        0      active sync   /dev/loop0
      1       7        1        1      active sync   /dev/loop1
      2       7        2        2      active sync   /dev/loop2
      3       7        3        3      active sync   /dev/loop3
      4       7        4        4      active sync   /dev/loop4
          UUID : b89aa5de:da1054f5:b052cc51:393d7435
        Events : 0.24

and /proc/mdstat:

[root@localhost junk]# cat /proc/mdstat

Personalities : [raid5]

md0 : active raid5 loop4[4] loop3[3] loop2[2] loop1[1] loop0[0]

     3840 blocks level 5, 64k chunk, algorithm 2 [5/5] [UUUUU]

unused devices: <none>

Now I fail (e.g.) /dev/loop0:
mdadm -f /dev/md0 /dev/loop0

and get:
[root@localhost junk]# mdadm --detail /dev/md0
/dev/md0:
       Version : 00.90.01
 Creation Time : Sun May 15 13:41:24 2005
    Raid Level : raid5
    Array Size : 3840
   Device Size : 960
  Raid Devices : 5
 Total Devices : 5
Preferred Minor : 0
   Persistence : Superblock is persistent

   Update Time : Sun May 15 13:49:20 2005
         State : clean, degraded
Active Devices : 4
Working Devices : 4
Failed Devices : 1
 Spare Devices : 0

        Layout : left-symmetric
    Chunk Size : 64K

   Number   Major   Minor   RaidDevice State
      0       0        0       -1      removed
      1       7        1        1      active sync   /dev/loop1
      2       7        2        2      active sync   /dev/loop2
      3       7        3        3      active sync   /dev/loop3
      4       7        4        4      active sync   /dev/loop4
      5       7        0       -1      faulty   /dev/loop0
          UUID : b89aa5de:da1054f5:b052cc51:393d7435
        Events : 0.27

and:

[root@localhost junk]# cat /proc/mdstat

Personalities : [raid5]

md0 : active raid5 loop4[4] loop3[3] loop2[2] loop1[1] loop0[5](F)

     3840 blocks level 5, 64k chunk, algorithm 2 [5/4] [_UUUU]

unused devices: <none>

continue failing drives:
[root@localhost junk]# mdadm -f /dev/md0 /dev/loop1
mdadm: set /dev/loop1 faulty in /dev/md0
[root@localhost junk]# mdadm -f /dev/md0 /dev/loop2
mdadm: set /dev/loop2 faulty in /dev/md0
[root@localhost junk]# mdadm -f /dev/md0 /dev/loop3
mdadm: set /dev/loop3 faulty in /dev/md0
[root@localhost junk]# mdadm -f /dev/md0 /dev/loop4
mdadm: set /dev/loop4 faulty in /dev/md0

now I get:
[root@localhost junk]# mdadm --detail /dev/md0
/dev/md0:
       Version : 00.90.01
 Creation Time : Sun May 15 13:41:24 2005
    Raid Level : raid5
    Array Size : 3840
   Device Size : 960
  Raid Devices : 5
 Total Devices : 5
Preferred Minor : 0
   Persistence : Superblock is persistent

   Update Time : Sun May 15 13:51:09 2005
         State : clean, degraded
Active Devices : 0
Working Devices : 0
Failed Devices : 5
 Spare Devices : 0

        Layout : left-symmetric
    Chunk Size : 64K

   Number   Major   Minor   RaidDevice State
      0       0        0       -1      removed
      1       0        0       -1      removed
      2       0        0       -1      removed
      3       0        0       -1      removed
      4       0        0       -1      removed
      5       7        4       -1      faulty   /dev/loop4
      6       7        3       -1      faulty   /dev/loop3
      7       7        2       -1      faulty   /dev/loop2
      8       7        1       -1      faulty   /dev/loop1
      9       7        0       -1      faulty   /dev/loop0

and:

Personalities : [raid5]

md0 : active raid5 loop4[5](F) loop3[6](F) loop2[7](F) loop1[8](F) 
loop0[9](F)

     3840 blocks level 5, 64k chunk, algorithm 2 [5/0] [_____]

unused devices: <none>

but I can still read the file on the filesystem that is mounted (ie in 
the "junk" dir).

Hope that contains all the info you need.

/Patrik

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