ADSM-L

Re: Inconsistent Backup Performance

1996-08-19 17:03:18
Subject: Re: Inconsistent Backup Performance
From: Paul Zarnowski <VKM AT CORNELLC.CIT.CORNELL DOT EDU>
Date: Mon, 19 Aug 1996 17:03:18 EDT
On Mon, 19 Aug 1996 16:33:31 -0400 Jim Kleberg said:
>        We are now testing ADSM UNIX backups using MVS as a server.  Even
>     though our testing environment is fairly well controlled, our data
>     transfers (over TCP/IP) vary widely (.4 to 1 MB/sec) over a 10mb
>     switched ethernet connection.  This is within a minute or 2 of each
>     test.
>        Does anyone have any ideas as to what to look for?

Performance testing is a tricky business.  If you are doing smallish tests,
then one thing you must beware of is AIX filesystem cacheing.  The second
test may pull pages out of memory cache buffers instead of off of disk.
Network I/O may not be your bottleneck.  Pulling the data off of disk is
more likely to be your bottleneck.

Paul Zarnowski                     Phone:   607/255-4757
Cornell Information Technologies   Fax:     607/255-6523
Cornell University                 US Mail: 315 CCC, Ithaca, NY 14853-2601
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