[ale] backing up /var -POSTGRES & LABEL

[Jeff Lightner]

" adding or removing a SCSI disk changes the disk device name but not the filesystem volume label"

Well there you go.  I found out about the disk device name changes some time back but hadn't figured labels with that (2 & 2 together do equal 4 apparently).   

I'm used to UNIX variants which don't change existing device names.  (Well Solaris did on tape drive devices but there was a way to tell it to do persistent binding.)

On my RHEL AS 3 systems I had to do quite a bit to get around the device name changes but that was using EMC PowerPath for SAN so the names weren't directly mounted but used as alternate physical paths for the pseudo devices.

-----Original Message-----
From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of Paul Cartwright
To: ale at ale.org
Sent: Thursday, February 22, 2007 9:01 AM
To: Atlanta Linux Enthusiasts
Subject: Re: [ale] backing up /var -POSTGRES & LABEL

On Thursday 22 February 2007 08:37, Jeff Lightner wrote:
> 1.) ?lsof /var (or fuser /var if you don't have lsof - lsof is far
> superior in my experience - I've found some things fuser won't show you
> that lsof does.)
list open files, wow, what a thought!
beats ps -ef for sure.

> In my earlier response to your question I had noted that often going to
> single user from a multi-user run level doesn't unmount /var - however
> booting into single user shouldn't mount anything but /.

to boot into single user, you need to change the default init state... I 
remember this: /etc/inittab;

# The default runlevel is defined here
id:5:initdefault:

>
> 2.) ?You could put a label on it but it's not necessary. ?
> Personally I've never understood the fascination with labels in Linux.
> It isn't always obvious later which partition goes with which label - if
> I'm interested in the device rather than the mount point I'd just as
> soon seen that in the fstab than try to figure it out. ? I gather the
> idea is that if you see the label it helps you know it's purpose but it
> seems easy enough to figure out purpose from the partition table and
> fstab.
according to 'man fstab' using LABELS is more "robust", but it still doesn't 
explain how to MAKE a label.. ( and I like using /dev/sdb? )
  Instead  of  giving  the  device explicitly, one may indicate the (ext2 or 
xfs) filesystem that is to be mounted by its UUID or volume label  
(cf.e2label(8) or  xfs_admin(8)),  writing LABEL=<label> or UUID=<uuid>, 
e.g., `LABEL=Boot' or `UUID=3e6be9de-8139-11d1-9106-a43f08d823a6'.  This will 
make  the  system  more robust: adding or removing a SCSI disk changes the 
disk device name but not the filesystem volume label.

-- 
Paul Cartwright
Registered Linux user # 367800
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