 | | | system down - can 't find luns (correction) | system down - can 't find luns (correction) 2005-05-23 - By Ed Wilts
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On Mon, May 23, 2005 at 11:02:36AM -0500, Rigler, Stephen C. wrote:
> On Mon, 2005-05-23 at 10:53 -0500, Dana Holland wrote:
> > Rigler, Stephen C. wrote:
> > > First, try doing "mount /dev/sdb1 /usr/local/bbls".
> > > If that works, then unmount and try doing "mount /usr/local/bbls".
> > >
> > > If the second try doesn't work, then make sure your filesystem has the
> > > label specified in the fstab ("e2label /dev/sdb1"). If it doesn't have
> > > the label, then you can relabel it by doing
> > > "e2label /dev/sdb1 /dev/sdb1". Repeat for /dev/sdc1.
> >
> > mount /dev/sdb1 /usr/local/bbls works - mount /usr/local/bbls doesn't work
> >
> > I guess I'm being dense, but I'm not following what you and Ed are
> > telling me about the label in /etc/fstab - here is what I have:
> >
> > LABEL=/dev/sdb1 /usr/local/bbls ext2 defaults 1 2
> > LABEL=/dev/sdc1 /usr/local/bbcm ext2 defaults 1 2
> >
> > What is it that's incorrect?
>
> The entries in your fstab are causing the system to mount filesystems by
> label rather than by the device file. The label makes things convenient
> because, if things devices change their mappings, you can still mount
> the filesystem because you know what it's label is. The labels can be a
> pain for the same reason (like if you want to change system disks).
For SCSI devices, it's usually considered mandatory to label the drives
- that's normally true for non-SAN drives but probably not as critical
for SAN storage.
What happens by default is that the first SCSI drive will be /dev/sda1.
The second drive will be /dev/sdb1. This may work fine for years, but
imagine what happens if /dev/sda1 fails on boot. Suddenly all of your
drives got renumbered and what used to be /dev/sdb1 is now /dev/sda1.
The purpose of the labels is to ensure that this doesn't happen - the
label can be anything and does not have to match the device name. In
your case, a more useful label would be something like bbls. So you
could have:
# e2label /dev/sda1 bbls
and in your fstab have:
LABEL=bbls /usr/local/bbls ...
When the device is ready to be mounted, there will be a scan for the
labels on all the disks your system can see, and when it finds one with
bbls, it will be mounted on /usr/local/bbls - you never need to know
that it's /dev/sdb1 at all.
> It should be pretty straight forward. I'm betting that whomever set up
> the mounts probably forgot to add the labels.
Given that the data is apparently intact, that's a safe bet.
Incidentally, unless your system is really old, now might be a good time
to convert the disk from ext2 to ext3 so that you've got a journalling
file system that recovers for errors a lot more cleanly.
.../Ed
--
Ed Wilts, RHCE
Mounds View, MN, USA
mailto:ewilts@(protected)
Member #1, Red Hat Community Ambassador Program
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