Has to do with fragmentation (at least with my Diligent VTL).  The VTL
wants contiguous space to allocate to virtual tapes.  I think I've
posted this script before, but feel free to take a look:

===================================

more /NB-scripts/label_script.sh
# more /usr/openv/util/label_script.sh
#!/bin/sh

# This script generates a list of media located on VTL which have
expired and     #
# have been returned to the Scratch pool since the last time the script
was run.  #
# It should be called on a regular basis from cron, or by a Netbackup
session     #
# notify script.
#

# Assumes /usr/openv/volmgr/tmp exists, and contains a file called
prev.scratch   #
# which contains a listing of the scratch tapes labelled on the previous
batch.   #

# Also, assumes this script is run as 'root'
#

# vmquery provides a list of all tapes in Scratch pool and residing in
the VTL    #
# and dumps this list to a temp file.
#
# NOTE HERE,  my VTL tapes start with "VT", change those characters to
your       #
# prefix if you'd like/need
#

/usr/openv/volmgr/bin/vmquery -pn Scratch -b | grep VT | sort | awk
'{print $1}' > /tmp/oihJKHb.tmp

# diff compares the curent list of Scratch to the list from the previous
#
# iteration of this script and stores the new IDs in a new temp file
#

/usr/bin/diff /NB-scripts/prev.scratch /tmp/oihJKHb.tmp | grep ">" | awk
'{print $2}'  > /tmp/pjKLJHn.tmp

# we now bplabel all of the new Scratch media
#
for i in `cat /tmp/pjKLJHn.tmp`; do
/usr/openv/netbackup/bin/admincmd/bplabel -m $i -d dlt -o -p Scratch;
done 2>&1

# The script is finished with the previous iteration's info, so we clean
up       #
# Once the bplabel is complete, we take today's list of total Scratch
and store   #
# it as prev.scratch for the next iteration.
#
/bin/mv /tmp/oihJKHb.tmp /NB-scripts/prev.scratch

# We also clean up the list of today's unique scratch
#
/bin/rm -f /tmp/pjKLJHn.tmp
# The script has now prepared the info required to run again.
#

===================================

-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of A Darren
Dunham
Sent: November 10, 2009 3:44 PM
To: veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Quick Erase Script (Windows)


On Tue, Nov 10, 2009 at 01:59:48PM -0500, Jeff Lightner wrote:
> We use Data Domain here and haven't seen that.   

It's not datadomain specific.  It would happen with any VTL.

If you have a small scratch pool (tapes tend to be reused shortly after
they expire) and you're not near capacity on your VTL, then you might
not notice.

If you have a lot more virtual tapes than you need, then your VTL will
need to retain a lot of data.  NBU never tells the VTL when a tape has
expired, so the data must remain.

> Are you running image cleanup jobs in NBU?

Image cleanup doesn't erase tapes.  So if the tape is on a VTL, it
contines to consume space.  Even if it has expired within NBU.

I'd love for NBU to have a checkbox (maybe on a per-pool or per-robot
basis) that would tell it to erase a tape when it expires if the tape is
in a robot slot.

-- 
Darren
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