If you're running one data stream per drive, you're going to find you're
understreaming to the drive as Rob suggested.  Try cutting down to four or
three drives.  Basically what I'd do is start reducing the number of drives
and you should see performance actually improving.  Stop reducing the number
when performance no longer improves.

Steve

-----Original Message-----
From: veritas-bu-admin AT Eng.Auburn DOT EDU
[mailto:veritas-bu-admin AT Eng.Auburn DOT EDU]On Behalf Of Porter, Eric
Sent: Wednesday, November 01, 2000 9:13 AM
To: 'Rob Worman'; 'veritas-bu AT mailman.eng.auburn DOT edu'
Subject: RE: [Veritas-bu] netbackup with 9840's


Rob,

Answers to your questions are below.
Your comments/suggestions (or anyone else's) are appreciated!

Thanks

Eric

**** Where is the data coming from as it's being written to these 9840's?

The data is being backed-up out of raw logical volumes.  These volumes are
on the same server as netbackup  (i.e. local) (They are copies generated
using emc timefinder).

**** How many 9840's are you using for backups?

I have 8 drives, I am using 7.  The scripts I am using split the list of raw
logical volumes into 7.  Then we start 7 backups each to tackle one set of
raw logical volumes.  The 8'th drive is reserved for backups of oracle
archive logs (done hourly).

**** Where is your data coming from?  Is it local on this media server, is
it on a SAN, is it on one or more segments of your LAN, etc?

Local for the important data  (about 2 Terabytes).
Some less serious stuff originates on a dedicated switched 100M Ethernet
(running full duplex).

**** Are you configured to use Multiplexing?

No... I am pushing a raw partition from the same system I figured
multiplexing would hurt not help.

**** with a 9840 drive (transfer rate of 10-20 MB/sec depending on
compression AND STREAMING) it would be real easy to 'underfeed' your drives
and therefore cripple your performance.

If the numbers in the netbackup GUI are to be believed I am getting 4 -- 5
MB/sec per tape drive.
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