[mythtv-users] Totally OT - but need help wit RAID5 array

[James Pifer]

On Fri, 2006-11-17 at 12:34 +0000, Robin Hill wrote:
> On Fri Nov 17, 2006 at 07:21:55AM -0500, James Pifer wrote:
> 
> > Ok, so you're saying run this command (with create?):
> > mdadm --create --verbose /dev/md0 --assume-clean --level=5 --raid-devices=3 /dev/hdb /dev/hdc dev/hdd
> >
> Yes
> 
> > Then, assuming that works ok and BEFORE mounting, run:
> > fsck /dev/md0
> > 
> Well, if you have enough disk space, then you may want to do a dd of
> /dev/md0 just in case.  I'm not sure it'll help much though - if fsck
> can't fix it here then you're pretty much stuffed anyway.
> 
> > If I get past that, then run:
> > mdmadm -a /dev/md0 /dev/hdd
> > 
> Yes - this'll hot-add the third disk.  You can monitor the rebuild
> progress through /proc/mdstat.
> 
> > Sound right? Do I need to do anything about "dev/hdd" or just ignore?
> > 
> Ignore it - it seems to be being ignored during the create process so it
> shouldn't come into things at all.
> 
> Fingers crossed,
>         Robin

Well, it won't seem to let me do it:
[root at storage ~]# mdadm --create --verbose /dev/md0 --assume-clean --level=5 --raid-devices=3 /dev/hdb /dev/hdc dev/hdd
mdadm: layout defaults to left-symmetric
mdadm: chunk size defaults to 64K
mdadm: /dev/hdb appears to contain an ext2fs file system
    size=312581632K  mtime=Wed Nov 15 09:54:22 2006
mdadm: /dev/hdb appears to be part of a raid array:
    level=raid5 devices=3 ctime=Wed Nov 15 09:42:22 2006
mdadm: /dev/hdc appears to be part of a raid array:
    level=raid5 devices=3 ctime=Wed Nov 15 09:42:22 2006
mdadm: Cannot open dev/hdd: No such file or directory
mdadm: create aborted

What do you think?

James