Re: Software RAID-5 crash
From: The Smalleys (charles_at_computerwise.cc)
Date: 09/29/04
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Date: Wed, 29 Sep 2004 04:06:24 GMT
I was wondering if you figured out what was wrong and how to fix it.
Also a recommendation for you.
If you really want to use RAID5, get yourself a hardware RAID 5 card.
It will perform much better than software raid.
Software Raid 0 (mirroring) works OK as far as performance, but Software
RAID5 is a lot slower.
If have run into the same problem as you only with a mirrored drive.
One of the partitions went offline and I could never get it back online.
That's another reason I prefer hardware raid over software raid.
I also learned with hardware raid that you must be sure the drivers match
and work with the
hardware. Just because you can get it set up and running doesn't mean that
the
array will rebuild when a drive goes bad and is replaced.
I suggest with any RAID systems (hardware and software.) When you initially
setup the system, put some known good data on it, simulate a drive failure
(pull the power cord on it.), See if after replacing it with another drive
that the system rebuilds and the data is still good.
Let me know if you figured out how to work with the software raid.
Thanks,
Charles Smalley
"Scott Odom" <scott@getwithme.nospam.com> wrote in message
news:pan.2004.09.16.13.38.08.141531@getwithme.nospam.com...
> I have a Mandrake 10 server with a 40gb boot drive and a three 200gb disk
> software raid 5 array using reiserfs. A disk went bad; so i have replaced
> it.
>
> Doing the normal things to get it back up don't work:
>
> #raidhotadd /dev/md0 /dev/hdg
>
> /dev/md0: can not hot-add disk: array not running!
>
> # raidstart -a
>
> /dev/md0: Invalid argument
>
> # mdadm --examine /dev/md0
> mdadm: /dev/md0 is too small for md
>
> raidhotremove /dev/md0 /dev/hdg1
> /dev/md0: can not hot-remove disk: array not running!
>
>
> Since the RAID is not "running" you cannot add or subtract drives. To do
> anything I will have to get it started.
>
> I think the superblock on the virtual disk is corrupt. Can anyone help?
> This is a production server and the backup was a removable drive that
> failed last week.
>
> Thanks
>
>
> # cat /etc/fstab
> /dev/hde1 / reiserfs notail 1 1
> none /dev/pts devpts mode=0620 0 0
> # /dev/md0 /files reiserfs notail 1 2
> /dev/hda /mnt/cdrom auto
> umask=0,user,iocharset=iso8859-1,codepage=850,noauto,ro,exec 0 0
> none /mnt/floppy supermount
> dev=/dev/fd0,fs=ext2:vfat,--,umask=0,iocharset=iso8859-1,sync,codepage=850
> 0 0
> none /proc proc defaults 0 0
> /dev/hde5 swap swap defaults 0 0
>
> # cat /etc/raidtab
> raiddev /dev/md0
> raid-level 5
> chunk-size 128k
> persistent-superblock 1
> nr-raid-disks 3
> device /dev/hdg1
> raid-disk 0
> device /dev/hdi1
> raid-disk 1
> device /dev/hdk1
> raid-disk 2
>
> dmesg:
> md: invalid raid superblock magic on hdg1
> md: hdg1 has invalid sb, not importing!
> md: could not import hdg1!
> md: autostart unknown-block(0,8705) failed!
>
> cat /proc/modules
> raid5 20512 0 - Live 0xd0a5e000
>
> # cat /proc/mdstat
> Personalities : [raid5]
> md0 : inactive hdi1[1] hdk1[2]
> 390716672 blocks
> unused devices: <none>
>
>
> # mdadm --examine /dev/md0
> mdadm: /dev/md0 is too small for md
>
>
> # raidhotremove /dev/md0 /dev/hdg1
> /dev/md0: can not hot-remove disk: array not running!
>
>
> # uname -a
> 2.6.3-7mdk
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