Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ucbvax!carleton.EDU!DNEIMAN
From: DNEIMAN@carleton.EDU.UUCP
Newsgroups: comp.os.vms
Subject: 6250 tape backup
Message-ID: <8706021924.AA04880@ucbvax.Berkeley.EDU>
Date: Mon, 1-Jun-87 10:30:00 EDT
Article-I.D.: ucbvax.8706021924.AA04880
Posted: Mon Jun  1 10:30:00 1987
Date-Received: Thu, 4-Jun-87 07:27:35 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: world
Organization: The ARPA Internet
Lines: 35


We have a 3-vax cluster (two 750's and a 780), all running VMS 4.5, connected
to a single HSC-50 (v300), and 5 RA-81's.  Currently, we have two TU-80 tape
drives with which we do our regular backup procedures.

We are considering the purchase of a 6250 bpi tape drive, which will replace
either or both of our current tape drives.  My questions:

Is is possible from the above information to determine whether and how much
the 6250 tape drive will speed up backup (Is the bottle neck tape throughput,
disk i/o, or cpu?).

More info:  This drive may or may not be placed on the HSC; it may go on
one of the other machines.  Is a 750 a reasonable place for a 6250 bpi drive?
How about a 780?  What are the performance tradeoffs?

Currently, backup is done on both tape drives simultaneously, performing
incremental backups on different disks.  Backup is usually done in the evening,
when the administrative machines are less loaded. We may purchase a sixth
RA-80, which will be backed up identically as the others.  Will the use of a
single 6250 bpi tape drive make backup slower overall?  How much will it
compensate for the simultaneous use (on different cpu's) of two 1600 bpi
drives? 

--------
Replies to me _may_ be summarized, they _will_ be appreciated.

Thank you,

Dave Neiman		Csnet:	DNeiman@carleton.edu
Carleton College	uucp:   ...{decvax|ihnp4}!stolaf!ccnfld!dneiman
Northfield, MN 55057-4040				(When in operation)
(507) 663-0545

Disclaimer:  "It all started when he hit me back..."