Soft-Raid Testing and other stuff...

[Ed Wilts]

On Tue, Jan 18, 2005 at 03:23:20PM -0000, Richard Hobbs wrote:
> I have built two RedHat 8.0 machines, both using soft-raid to mirror one
> 250GB disk onto the other identical 250GB disk inside the case.
> 
> During the install, I created the RAID partitions, and assigned them to
> actual partitions, and now I have "/dev/md0" up to "/dev/md7".
> 
> However, each time I boot and each time I shut down, I get the following
> message:
> 
>   No spare disk to reconstruct array! -- running in degraded mode.
> 
> What exactly does this mean? Both drives are visible from the BIOS, and the
> jumpers are set to Cable Select (not Master and Slave).
> 
> Despite the above error message, the machine boots fine, shuts down fine,
> and runs fine.

When it's up, cat /proc/mdstat
 
> However, if I unplug the master hard drive, it will not boot from the
> secondary, even if I plug it into the primary socket on the IDE cable.

Did you duplicate the MBR to the second drive?  If you didn't, you won't
boot.  Remember that you've only mirrored the data partitions, not the
boot block.

> I have even tried inserting a third 250GB hard drive on the secondary IDE
> channel to see if that would become the spare disk it needs to reconstruct
> the array, but that didn't work either.

I wouldn't expect it to.  I would not be happy if the software just
grabbed an extra drive and toasted the data on it unless I explicitely
told it to.
 
-- 
Ed Wilts, RHCE
Mounds View, MN, USA
mailto:ewilts at ewilts.org
Member #1, Red Hat Community Ambassador Program