Re: [Dump-users] Help with full and incremental dumps

[Kenneth P. <sh...@se...>]

Just saw your post on the CentOS list about this:

<http://lists.centos.org/pipermail/centos/2007-December/091795.html>

Another dump user pointed out to me the value of using LVM snapshots to 
dump a "live" filesystem. You need a little extra space on the disk to hold 
the filesystem changes while the snapshot is in effect (ie. for the 
duration of the dump, and perhaps the verify if you do that).

------------ Forwarded Message ------------
Date: Thursday, December 20, 2007 12:31 AM +0000
From: "Keith G. Robertson-Turner" <dum...@ge...>
To: Kenneth Porter <sh...@se...>
Subject: Re: [Dump-users] Missing files on verify, hard link issue?

Verily I say unto thee, that Kenneth Porter spake thusly:
> --On Friday, December 14, 2007 2:16 PM -0800 Kenneth Porter
> <sh...@se...> wrote:

>> On my first attempt I still ended up with a couple of missing files
>> in the  pool.

I strongly suggest you investigate LVM, it'll save you a lot of hassle
trying to dump a live filesystem.

Here's a condensed version of my server's backup script, as an example:

level=$(expr $(date +%u) - 1)
lvcreate -l100%FREE -s -n var-snapshot /dev/cumulous/var
mount -t ext3 /dev/cumulous/var-snapshot /mnt/snapshots/var
dump -${level}u -z -E /mnt/WD_Passport/sky.backup/var.exceptions \
   -f /mnt/WD_Passport/sky.backup/${level}/var.dump /mnt/snapshots/var
umount /mnt/snapshots/var
lvremove -f /dev/cumulous/var-snapshot

It really is that simple. All you have to do is format your drive(s)
with LVM, and remember to leave some unused slack at the end (I leave
about 1GB, which has always been enough for that very busy server).

-- 
Regards,
Keith G. Robertson-Turner

---------- End Forwarded Message ----------

>From your CentOS post:

> Trying to adapt the knowledge to a tape library...
>
> /sbin/dump -0 -v -z2 -f /dev/nst0 /var/log
> /sbin/dump -0u -v -z2 -f /dev/nst0 /home
>
> I have a cron job that dumps the results to /var/log/dump.log, and a
> review of the log file claims all went well.  Now for the restore...
>
> I just tried playing with different options of restore, but could not
> successfully restore anything.   I ensured I was in a scratch area so as
> to hopefully not overwrite current files.

What options did you try with restore? What tape positioning and library 
commands do you use? (I believe mt is the command used to move the tape to 
the desired dump file before issuing restore.)

For testing, try the -C option (compare). I use that following every dump 
to make sure the data got to the tape. (I'm using an external USB drive 
now, but I used to use DAT tape on SCSI quite successfully.)