[Veritas-bu] DLT7000 on HPUX11i, NB 4.5 Only Goes Up to 35GB Capacity

2003-12-10 00:00:53
Subject: [Veritas-bu] DLT7000 on HPUX11i, NB 4.5 Only Goes Up to 35GB Capacity
From: rob AT worman DOT org (Rob Worman)
Date: Tue, 9 Dec 2003 23:00:53 -0600
Hello Nelson-

It sounds like you are have enabled the NetBackup policy 
"compression" attribute, which is essentially software compression, 
i.e. the NetBackup client does a "compress" on every file before that 
file gets sent to the media server and written to tape.  This 
software compression is a feature that most customers rarely use in 
this era of fast networks and efficient compression embedded in 
modern tape drives.

With software compression enabled, it it not suprising to hear that 
you're filling up your DLT tapes with only 35GB of data.  (by the 
time your data reaches the tape drive, it is definitely NOT 

I'd suggest that you turn off the policy compression attribute and 
repeat your testing - I bet you'll see the capacity you expect from 
your DLT7000 drives.  (if you only back up text files full of zeroes, 
I bet you'll fit a few hundred gigs of data on each tape  ;-))


At 11:42 PM -0500 12/9/03, Nelson T. Caparroso wrote:
>We've been on test-mode the past seevral days and we notice 
>available_media reports FULL tapes at being filled to no more than 
>35GB capacity even if we don't set the Policies to do compression 
>and the backup sets are highly compressible. Netbackup is using the 
>device entries in the form of /dev/rmt/c8t0d2BESTnb -- which is the 
>bsd BEST density device on HPUX systems... It supposedly offers 
>compression laready but an "lssf" or mt stat on the device file does 
>not echo out a status that will seem to indicate  has compression... 
>I know that I canmanually create a compression device file using 
>"mksf -d stape -c....." but isn't Netbackup on HPUX11i  set to 
>automatically confiure the best (compression) device entries for the 
>ANyone running Netbackup 4.5 on HPUX and DLT7000 drives? Please 
>could you check what device entries you're using and whether you can 
>go veyond the 35GB native capcity?
>Veritas-bu maillist  -  Veritas-bu AT mailman.eng.auburn DOT edu

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