[Veritas-bu] DLT7000 Speed
sdvorak at veritas.com
Thu Oct 18 10:57:33 CDT 2001
There are a few things to check. One would be shared memory settings.
There is some kernel tuning to do to add shared memory which will allow you
to utilize more memory when backing up locally. Each DLT 7000 drive
requires 64MB dedicated to it. NBU also requires memory and has some
tunables that will allow you to take advantage of the extra allocated
You should be able to get 5-7MB/sec which would give you 18GB-25GB/hr. Keep
in mind that the disk subsystem can still be a bottleneck to getting that
throughput. If you have millions of small files on the file systems that
you are backing up, you will see slower backup speeds, and might think about
trying the FlashBackup Option for NetBackup (check with your local sales
Also, the suggestion about running regular TAR to your tape device is a good
one. You can also check disk subsystem speed by TAR'ing to /dev/null. Keep
in mind that TAR uses a different default block size than NBU.
From: benr at cuddletech.com [mailto:benr at cuddletech.com]
Sent: Wednesday, October 17, 2001 4:35 PM
To: Veritas-bu at mailman.eng.auburn.edu
Subject: [Veritas-bu] DLT7000 Speed
Any thoughts on this? I'm doing some big backups to a DLT7000 (via a ADIC
Scalar 2x tape robot). My backup is 400G and running on a single drive.
It's currently averaging 1500k/s. The problem with this speed is that comes
out to 5.4G/hr. Isn't that alittle slow? Can NetBackup throttle drives and
thus slow down my backup this way? Or is there something I can look to
change? The disk system on the system (this is a local backup) isn't really
being taxed, and it's a Fibre Channel disk system with striped volumes. The
system is a Sun Enterprise 4500 running Solaris 2.6 with NetBackup 3.2.
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