Re: Software RAID problems (bad filesystem type)

[Justin Guerin <jguerin@cso.atmel.com>]

On Monday 09 February 2004 11:05, Timo Railo wrote:
[snip]
> > Your fstab file for your raid device is correct.  What does your /etc/
> > raidtab and /etc/raid/raidtab look like?  /etc/raidtab should be a link
> > to /etc/raid/raidtab.  Post the contents of /etc/raid/raidtab, and we
> > may be more able to pinpoint your problem.
>
> Actually, I think that didn't exist at all (I think mdadm doesn't
> really care that much for raidtab at all). I've created one manually,
> while trying another route, and it looks like this (no
> /etc/raid/raidtab at all):
>
> raiddev /dev/md0
>          raid-level      linear
>          nr-raid-disks   2
>          chunk-size      32
>          persistent-superblock   1
>          device          /dev/hdc2
>          raid-disk       0
>          device          /dev/hdc
>          raid-disk       1
>
You're going to have problems with that setup.  You can't have a raid using 
part of a disk (hdc2) and the entire disk (hdc).  You should be using two 
partitions, like this:
# cat /etc/raid/raidtab
raiddev /dev/md0
raid-level 1
nr-raid-disks 2
nr-spare-disks 0
chunk-size 4
persistent-superblock 1
device /dev/hda2
raid-disk 0
device /dev/hdc1
raid-disk 1

Also note that you'll get much better performance if you can separate your 
disks onto individual IDE busses.  For my machine, I moved one disk from 
the slave on the first bus (hdb) to the master on the second bus (hdc), and 
now I've got a quicker setup.  But you can still make RAID work on one 
disk / IDE bus, if you need to / have to.

> > Also, provide the output of "cat /proc/mdstat".  You should see
> > something
> > like this:
> > Personalities : [raid1]
> > read_ahead 1024 sectors
> > md0 : active raid1 hdc1[1] hda2[0]
> >       15936 blocks [2/2] [UU]
>
> Personalities : [raid1]
> read_ahead not set
> unused devices: <none>
>
This means that you're drives aren't properly recognized.  You'll have to 
fix your raidtab and then start the raid.  I didn't use mdadm, so I'm not 
sure of the syntax.  But since you've actually got a /proc/mdstat, that 
means your drivers are loaded.

> Thanks Justin!!!
>
> Timo
You're welcome.

Justin Guerin