how to tell if raid1 array is REALLY working?

[Harland Christofferson <debian-user@zerocrossings.com>]

Hi all,

On one machine, I have a raid1 array consisting of /dev/hda and /dev/hdc.
A few days ago, just for fun, I tried to mount a partition of /dev/hdc 
to /mnt 

# mount /dev/hdc6 /mnt/hdc6

the response I receive was:

mount: wrong fs type, bad option, bad superblock on /dev/hdc6,
       or too many mounted file systems

hmm ... so, I tried

# fdisk -l /dev/hdc

Disk /dev/hdc: 16 heads, 63 sectors, 79656 cylinders
Units = cylinders of 1008 * 512 bytes

   Device Boot    Start       End    Blocks   Id  System
/dev/hdc1   *         1        64     32098+  83  Linux
Partition 1 does not end on cylinder boundary:
     phys=(3, 254, 63) should be (3, 15, 63)
/dev/hdc2            64     79401  39985785    5  Extended
Partition 2 does not end on cylinder boundary:
     phys=(1023, 254, 63) should be (1023, 15, 63)
/dev/hdc5            64      1052    497983+  82  Linux swap
/dev/hdc6          1052     39812  19535008+  83  Linux
/dev/hdc7         39812     59192   9767488+  83  Linux
/dev/hdc8         59192     79401  10185178+  83  Linux

Interesting, I thought. Then, I tried:

# mdadm -D /dev/md0

/dev/md0:
        Version : 00.90.00
  Creation Time : Thu Dec  9 12:44:16 2004
     Raid Level : raid1
     Array Size : 40021568 (38.16 GiB 40.98 GB)
    Device Size : 40021568 (38.16 GiB 40.98 GB)
     Raid Disks : 2
    Total Disks : 2
Preferred Minor : 0
    Persistance : Superblock is persistant

    Update Time : Thu Dec  9 12:44:16 2004
          State : dirty, no-errors
  Active Drives : 2
 Working Drives : 2
  Failed Drives : 0
   Spare Drives : 0


    Number   Major   Minor   RaidDisk   State
       0       3        0        0      active sync   /dev/hda
       1      22        0        1      active sync   /dev/hdc
           UUID : 1dc497ab:ef9a2366:a9c762f3:301b6de7

Everything except the partition table looks good. I thought to check 
/proc/mdstat as well:

# cat /proc/mdstat

Personalities : [raid1] 
read_ahead 1024 sectors
md0 : active raid1 ide/host0/bus1/target0/lun0/disc[1] ide/host0/bus0/target0/lun0/disc[0]
      40021568 blocks [2/2] [UU]
      
unused devices: <none>

So, the raid information seems correct but the partition table information 
seems incorrect and I cannot mount and partitions on /dev/hdc (except 
for /dev/hdc1). How can I fix the problem of mounting and how can 
I know if the array truly is correct?

Regards,
Harland


http://www.zerocrossings.com/