Re: Raid 5 Problem

[nterry <nigel@nigelterry.net>]

Michal Soltys wrote:
> nterry wrote:
>>
>> Great - All working.  Then I rebooted and was back to square one with 
>> only 3 drives in /dev/md0 and /dev/sdb in /dev/md_d0
>>                                   So I am still not understanding 
>> where /dev/md_d0 is coming from and although I know how to get things 
>> working after a reboot, clearly this is not a long term solution...
>>
>
> My blind shot is that udev rules of your distro are doing mdadm 
> --incremental assembly and picking sdb as a part of nonexisting array 
> from the long ago (leftover after old experimentations ?). Or 
> something else is doing so.
>
> What does mdadm -Esvv /dev/sdb show ?
>
> Add
>
> DEVICE /dev/sd[bcde]1
>
> on top of your mdadm.conf - it should stop --incremental from picking 
> up sdb. Assuming that's the cause of the problem.
>
> Also note, that FC9 might be trying to assemble the array during 
> initramfs stage (assuming it uses one) and having problems there. I've 
> never used Fedora so hard to tell for me - but definitely peek there, 
> particulary at udev and mdadm part of things.
>
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[root@homepc ~]# mdadm -Esvv /dev/sdb
/dev/sdb:
          Magic : a92b4efc
        Version : 0.90.02
           UUID : c57d50aa:1b3bcabd:ab04d342:6049b3f1
  Creation Time : Thu Dec 15 15:29:36 2005
     Raid Level : raid5
  Used Dev Size : 245111552 (233.76 GiB 250.99 GB)
     Array Size : 245111552 (233.76 GiB 250.99 GB)
   Raid Devices : 2
  Total Devices : 3
Preferred Minor : 0

    Update Time : Wed Apr  5 13:43:20 2006
          State : clean
 Active Devices : 2
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 1
       Checksum : 2bd59790 - correct
         Events : 1530654

         Layout : left-symmetric
     Chunk Size : 128K

      Number   Major   Minor   RaidDevice State
this     2      22        0        2      spare

   0     0       8        1        0      active sync   /dev/sda1
   1     1       8       17        1      active sync   /dev/sdb1
   2     2      22        0        2      spare
[root@homepc ~]#

I added the DEVICE /dev/sd[bcde]1 to mdadm.conf and that apepars to have 
fixed the problem.  2 reboots and it worked both times.

I also note now that:
[root@homepc ~]# mdadm --examine --scan
ARRAY /dev/md0 level=raid5 num-devices=4 
UUID=50e3173e:b5d2bdb6:7db3576b:644409bb
   spares=1
[root@homepc ~]#

Frankly I don't know enough about the workings of udev and the boot 
process to be able to get into that.  However these two files might mean 
something to you:

[root@homepc ~]# cat /etc/udev/rules.d/64-md-raid.rules
# do not edit this file, it will be overwritten on update

SUBSYSTEM!="block", GOTO="md_end"
ACTION!="add|change", GOTO="md_end"

# import data from a raid member and activate it
#ENV{ID_FS_TYPE}=="linux_raid_member", IMPORT{program}="/sbin/mdadm 
--examine --export $tempnode", RUN+="/sbin/mdadm --incremental 
$env{DEVNAME}"
# import data from a raid set
KERNEL!="md*", GOTO="md_end"

ATTR{md/array_state}=="|clear|inactive", GOTO="md_end"

IMPORT{program}="/sbin/mdadm --detail --export $tempnode"
ENV{MD_NAME}=="?*", SYMLINK+="disk/by-id/md-name-$env{MD_NAME}"
ENV{MD_UUID}=="?*", SYMLINK+="disk/by-id/md-uuid-$env{MD_UUID}"

IMPORT{program}="vol_id --export $tempnode"
OPTIONS="link_priority=100"
ENV{ID_FS_USAGE}=="filesystem|other|crypto", ENV{ID_FS_UUID_ENC}=="?*", 
SYMLINK+="disk/by-uuid/$env{ID_FS_UUID_ENC}"
ENV{ID_FS_USAGE}=="filesystem|other", ENV{ID_FS_LABEL_ENC}=="?*", 
SYMLINK+="disk/by-label/$env{ID_FS_LABEL_ENC}"

LABEL="md_end"
[root@homepc ~]#

AND...

[root@homepc ~]# cat /etc/udev/rules.d/70-mdadm.rules
# This file causes block devices with Linux RAID (mdadm) signatures to
# automatically cause mdadm to be run.
# See udev(8) for syntax

SUBSYSTEM=="block", ACTION=="add|change", ENV{ID_FS_TYPE}=="linux_raid*", \
    RUN+="/sbin/mdadm -I --auto=yes $root/%k"
[root@homepc ~]#

Thanks for getting me working

Nigel