Problems creating RAID 5 using mdadm

[Stephan Ruggiero <stephan.ruggiero@rad.ma.uni-heidelberg.de>]

Hello,

I've been messing around with problem for over a week now and did not  
find any solution, so this is why I hope to find help in this way...

I have a fresh debian sarge installation (kernel 2.6.8-2-386) on a  
RAID 1 array (this array was created during the installation process  
using the debian setup routine).
The RAID1 array /dev/md0 consists of 2 different hard disks and works  
fine.

Now I have 4 separate hard disks (400 GB each) and I want to to use  
them in a RAID 5 array.
So I did create a blank "Linux raid autodetect" partition on each of  
the 4 hard disks using fdisk, this is what "fdisk -l" gives me:
__________________________
fdisk -l /dev/sda

Disk /dev/sda: 400.0 GB, 400088457216 bytes
255 heads, 63 sectors/track, 48641 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1       48641   390708801   fd  Linux raid  
autodetect
__________________________
(same for /dev/sdb, /dev/sdc and /dev/sdd)

Then I did:
mdadm --create --force /dev/md1 --level=raid5 --chunk=64 -- 
parity=left-symmetric --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 / 
dev/sdd1

After the sync had finished, I wrote the new mdadm config file:
mdadm --detail --scan > /etc/mdadm/mdadm.conf
I added a DEVICE line, becaus I read this would help the arrays to be  
recognized. This is how the mdadm.conf looks like:
__________________________
DEVICE /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/hda1 /dev/hdb1
ARRAY /dev/md1 level=raid5 num-devices=4  
UUID=a2e5426c:b2830333:accac389:9393124d
   devices=/dev/sda1,/dev/sdb1,/dev/sdc1,/dev/sdd1
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=b5e33bba: 
3509dbed:aed82fc4:46628aec
   devices=/dev/hda1,/dev/hdb1
__________________________

Then I created the file system:
mkfs.ext3 -b 4096 -R stride=16 /dev/md1

I edited the /etc/fstab, it looks like this:
__________________________
# /etc/fstab: static file system information.
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults        0       0
/dev/md0        /               ext3    defaults,errors=remount-ro  
0       1
/dev/md1        /pacs           ext3    defaults        0       2
/dev/hda3       /tmp            ext3    defaults        0       2
/dev/hdb3       /tmp2           ext3    defaults        0       2
/dev/hda2       none            swap    sw              0       0
/dev/hdb2       none            swap    sw              0       0
/dev/hdc        /media/cdrom0   iso9660 ro,user,noauto  0       0
/dev/fd0        /media/floppy0  auto    rw,user,noauto  0       0
__________________________
(the /pacs mount point exists)

When rebooting, the fsck fails, giving me the following warning:
__________________________
fsck.ext3: Invalid argument while trying to open /dev/md1
/dev/md1:
The superblock could not be read or does not describe a correct ext2  
filesystem. If the device is valid and it really contains an ext2  
filesystem (and not swap or ufs or something else), then the  
superblock is corrupt, and you might try running e2fsck with an  
alternate superblock:
e2fsck -b 8193 <device>
__________________________

I continue the boot process, then the /proc/mdstat looks like this:
__________________________
Personalities : [raid1]
md0 : active raid1 hda1[0] hdb1[1]
      39061952 blocks [2/2] [UU]

unused devices: <none>
__________________________

Then I do "mdadm -A -s", it gives:
mdadm: /dev/md1 has been started with 4 drives.

and the /proc/mdstat:
__________________________
Personalities : [raid1] [raid5]
md1 : active raid5 sda1[0] sdd1[3] sdc1[2] sdb1[1]
      1172126208 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU]

md0 : active raid1 hda1[0] hdb1[1]
      39061952 blocks [2/2] [UU]

unused devices: <none>
__________________________

This is what I get with "mdadm --examine /dev/sda1":
__________________________
/dev/sda1:
          Magic : a92b4efc
        Version : 00.90.00
           UUID : a2e5426c:b2830333:accac389:9393124d
  Creation Time : Tue May  9 09:33:20 2006
     Raid Level : raid5
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 1

    Update Time : Tue May  9 18:52:03 2006
          State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
  Spare Devices : 0
       Checksum : defd3829 - correct
         Events : 0.12

         Layout : left-symmetric
     Chunk Size : 64K

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

   0     0       8        1        0      active sync   /dev/sda1
   1     1       8       17        1      active sync   /dev/sdb1
   2     2       8       33        2      active sync   /dev/sdc1
   3     3       8       49        3      active sync   /dev/sdd1
__________________________


I can mount the array without problems, but I cannot read/write on it:
mount -t ext3 /dev/md1 /pacs

Can you please help me with that?

Thank you _very_ much in advance!

Best regards,

Stephan