Setting up Ubuntu 10.04 on software raid fails

[Willi Geffers]

Hi,

I'm in trouble with the raid setup procedure of the Ubtuntu installer
(text mode). I've tried to install Ubuntu 10.04 (64-bit) on a Dell
Precision M6400 with 2 hard disks partitioned identically

    # sfdisk -l /dev/sda
       Device Boot Start     End   #cyls    #blocks   Id  System
    /dev/sda1          0+    486-    487-   3905536   fd  Linux raid
autodetect
    /dev/sda2        486+   1458-    973-   7812096   fd  Linux raid
autodetect
    /dev/sda3       1459+  60801-  59343- 476666881    5  Extended
    /dev/sda4          0       -       0          0    0  Empty
    /dev/sda5       1459+   1945-    487-   3905536   fd  Linux raid
autodetect
    /dev/sda6       1945+   2917-    973-   7811072   fd  Linux raid
autodetect
    /dev/sda7       2917+  60801-  57884- 464948224   fd  Linux raid
autodetect

a software raid configuration with 5 2-way mirrors

    md4 : active raid1 sdb7[1] sda7[0]
          464948160 blocks [2/2] [UU]

    md2 : active raid1 sdb5[1] sda5[0]
          3905472 blocks [2/2] [UU]

    md3 : active raid1 sdb6[1] sda6[0]
          7811008 blocks [2/2] [UU]

    md1 : active raid1 sdb2[1] sda2[0]
          7812032 blocks [2/2] [UU]

    md0 : active raid1 sda1[0] sdb1[1]
          3905472 blocks [2/2] [UU]

to be mounted/used as follows

    Device      Filesystem    Size    Mounted on
    /dev/md0    ext4          1.9G    /
    /dev/md1    swap          7.4G    -
    /dev/md2    ext4          3.7G    /var
    /dev/md3    ext4          7.4G    /usr
    /dev/md4    ext4          445G    /export

After installation the system complains about /dev/md4 and the whole
raid configuration looks corrupt and strange

    # cat /proc/mdstat 
    md0 : active raid1 md4p1[0]
          3905472 blocks [2/1] [U_]
      
    md1 : active raid1 md4p2[0]
          7812032 blocks [2/1] [U_]
      
    md2 : active raid1 md4p5[1]
          3905472 blocks [2/1] [_U]
      
    md3 : active raid1 md4p6[0]
          7811008 blocks [2/1] [U_]
      
    md4 : active raid1 sdb[1] sda[0]
          464948160 blocks [2/2] [UU]

The system log contains corresponding lines

    [    4.307147] md4: detected capacity change from 0 to 476106915840
    [    4.308112]  md4: p1 p2 p3 < p5 p6 p7 >
    [    4.386639] md4: p7 size 929896448 exceeds device capacity,
limited to end of disk


Everything works, if I do not configure /dev/md4 during installation,
but configure it manually afterwards using

    # mdadm --create --verbose /dev/md4 --auto=yes --level=1
--raid-devices=2 /dev/sda7 /dev/sdb7

and update /etc/mdadm/mdadm.conf

    # mdadm --detail --scan
    ARRAY /dev/md4 level=raid1 num-devices=2
UUID=efdae077:2c386400:55e4cae4:925f5df7

Has anybody experienced a similar behaviour?

Thanks
Willi
-- 
RWTH Aachen University            mailto:geffers at informatik.rwth-aachen.de
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