Ok - it looks like the raid array is up. There will have been an event count
mismatch which is why you needed --force. This may well have caused some
(hopefully minor) corruption.

FWIW, xfs_check is almost never worth running :) (It runs out of memory easily).
xfs_repair -n is much better.

What does the end of dmesg say after trying to mount the fs?

Also try:
xfs_repair -n -L

I think you then have 2 options:
* xfs_repair -L
This may well lose data that was being written as the drives crashed.
* contact the xfs mailing list

David

Chris Eddington wrote:

Hi David,

I ran xfs_check and get this:
ERROR: The filesystem has valuable metadata changes in a log which needs to
be replayed.  Mount the filesystem to replay the log, and unmount it before
re-running xfs_check.  If you are unable to mount the filesystem, then use
the xfs_repair -L option to destroy the log and attempt a repair.
Note that destroying the log may cause corruption -- please attempt a mount
of the filesystem before doing this.

After mounting (which fails) and re-running xfs_check it gives the same
message.

The array info details are below and seems it is running correctly ??  I
interpret the message above as actually a good sign - seems that
xfs_check sees the filesystem but the log file and maybe the most
currently written data is corrupted or will be lost.  But I'd like to
hear some advice/guidance before doing anything permanent with
xfs_repair.  I also would like to confirm somehow that the array is in
the right order, etc.  Appreciate your feedback.

Thks,
Chris



--------------------
cat /etc/mdadm/mdadm.conf
DEVICE /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1
ARRAY /dev/md0 level=raid5 num-devices=4
UUID=bc74c21c:9655c1c6:ba6cc37a:df870496
MAILADDR root

cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sda1[0] sdd1[2] sdb1[1]
     1465151808 blocks level 5, 64k chunk, algorithm 2 [4/3] [UUU_]
    unused devices: <none>

mdadm -D /dev/md0
/dev/md0:
       Version : 00.90.03
 Creation Time : Sun Nov  5 14:25:01 2006
    Raid Level : raid5
    Array Size : 1465151808 (1397.28 GiB 1500.32 GB)
   Device Size : 488383936 (465.76 GiB 500.11 GB)
  Raid Devices : 4
 Total Devices : 3
Preferred Minor : 0
   Persistence : Superblock is persistent

   Update Time : Fri Nov  9 16:26:31 2007
         State : clean, degraded
Active Devices : 3
Working Devices : 3
Failed Devices : 0
 Spare Devices : 0

        Layout : left-symmetric
    Chunk Size : 64K

          UUID : bc74c21c:9655c1c6:ba6cc37a:df870496
        Events : 0.4880384

   Number   Major   Minor   RaidDevice State
      0       8        1        0      active sync   /dev/sda1
      1       8       17        1      active sync   /dev/sdb1
      2       8       49        2      active sync   /dev/sdd1
      3       0        0        3      removed



Chris Eddington wrote:

quoted

Thanks David.

I've had cable/port failures in the past and after re-adding the
drive, the order changed - I'm not sure why, but I noticed it sometime
ago but don't remember the exact order.

My initial attempt to assemble, it came up with only two drives in the
array.  Then I tried assembling with --force and that brought up 3 of
the drives.  At that point I thought I was good, so I tried mount
/dev/md0 and it failed.  Would that have written to the disk?  I'm
using XFS.

After that, I tried assembling with different drive orders on the
command line, i.e. mdadm -Av --force /dev/md0 /dev/sda1, ... thinking
that the order might not be right.

At the moment I can't access the machine, but I'll try fsck -n and
send you the other info later this evening.

Many thanks,
Chris