[CentOS] problem with swap and upgrade to 4 from 3.3

[Daniel J. Cody]

Hey Peter,

Peter Farrow wrote:
> I note on other machines I have installed when the swap was mirrored on 
> the original install, it still appears to enable swap prior to the RAID 
> subsystem, without any errors.  So I guessed this might be a problem 
> with the ram disk image, so I created a new one using mkinitrd, but the 
> swap still fails at startup, thus preventing me from using the CDs to 
> upgrade the box.
> 
> I guess I could set the swap back to an unmirrored set, run the upgrade 
> from the CDs then mirror it again, but this is not ideal, does anyone 
> have any suggestions as to how to fix this little RAID niggle with the 
> swap caused by not RAIDing the swap parition originally on install?

I wouldn't personally recommend using software raid on swap partitions 
since it causes all sorts of problems like you're describing. If you 
want to get raid type performance from your swap partitions, I'd suggest 
just letting the kernel itself handle that.

All you need is to define each of the swap partitions in your /etc/fstab 
like so:

/dev/sda3       swap           swap    defaults,pri=1   0 0
/dev/sdb2       swap           swap    defaults,pri=1   0 0
/dev/sdc1       swap           swap    defaults,pri=1   0 0

That would set up parrallel swap on 3 scsi disks and might get you 
through your problem..

HTH

Dan