Veritas-bu

[Veritas-bu] tape drive performance on image copies

2002-08-28 12:10:38
Subject: [Veritas-bu] tape drive performance on image copies
From: CBallowe AT usg DOT com (Ballowe, Charles)
Date: Wed, 28 Aug 2002 11:10:38 -0500
are you using a read host that is the same as your write host, things
go much faster with -altreadhost rather than reading on one drive,
sending data over the network, and writing on a different host.

just a thought

> -----Original Message-----
> From: Eric Forgette [mailto:epforgette AT overnite DOT com]
> Sent: Wednesday, August 28, 2002 10:15 AM
> To: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: [Veritas-bu] tape drive performance on image copies
> 
> 
> I wrote a perl script to duplicate the most recent, successful, full
> backup images for a particular class.  The script is available at
> http://perlvault.sourceforge.net/ (beta release still...)
> 
> The problem I am having is in the performance of the image copies.  My
> expectation was that the tape to tape copies would be faster than the
> backups themselves.  The regular backup performance is limited by the
> fact that there are tons of small files and by the network speed / cpu
> speed of the client.  My understanding is that the images 
> (once on tape)
> are one sequential file, which should lend itself well to copying.
> 
> The master is an E4500 running Solaris 5.8.  I am using LTO 
> drives which
> are SAN attached.  I've seen throughput (using iostat) of 11 MB/second
> during regular backups.  During the image copies, I get between 5 - 7
> MB/second.  The regular backups do not use any multiplexing.
> 
> Is there any tuning parameters I can tweak?  
> Anyone have any ideas?
> 
> Regards,
> -Eric
> -- 
> Eric Forgette
> Unix Systems Administrator
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