This doesn't impact my comment, but are you talking about 9840Cs?  I didn't
realize there was such a thing until I saw a link on the STK site.  However,
the link is bad and I can't see any specs.

I run 9840Bs and I would say that 18MBps is too high of an estimate.  I
routinely see 25-30MBps for large solid files like SQL database backup files
that have already been written to disk, but I rarely see 18MBps for regular
server backups.  I also back up a lot of images (average size 50K), and they
run 5-8MBps.  The low performance of things like the image backups is mainly
OS overhead.  The servers that back them up are ES7000 partitions, the files
are on LUNs presented to the ES7000, and the tape drives are FC/SSO.

Matt

-----Original Message-----
From: Letnes, David G. [mailto:david.letnes AT unisys DOT com] 
Sent: Wednesday, July 30, 2003 6:19 PM
To: 'veritas-bu AT mailman.eng.auburn DOT edu'
Subject: [Veritas-bu] 9840 tape drive question


  I am trying to calculate how many drives it will take to backup our data
for a new silo we are pricing out.  The tape drives will be 9840's and I am
using the max speed of 18 MBps which is about 65 Gig an hour?    The formula
I am using looks like this...



                           Backup Data Volume
                     ------------------------------------------
= How many drives you will need
                Tape drive throughput    *    backup window


The speed I rated the 9840 tape drive; is that about 65 Gig an hour?

Are there any other formulas people use to determine how many tape drives
you will need?

Thanks
David




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