ADSM-L

Re: "LAN-free": does that have any meaning on the server??

2007-02-13 18:44:50
Subject: Re: "LAN-free": does that have any meaning on the server??
From: James R Owen <Jim.Owen AT YALE DOT EDU>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Tue, 13 Feb 2007 18:44:33 -0500
Allen,

Good news:
Your I/O is "LAN-free" because your 3292 drives are FC connected.

Bad news:
For LAN-free backups, the TSM StgAgent drives the tape I/O.
For tape-tape reclamation the TSM Server drives the tape I/O.

All of the I/O is going through and driven by the host server
subject to its bus and CPU limitations.
--
Jim.Owen AT Yale DOT Edu   (203.432.6693)
No free lunch (except served by others at a soup kitchen.)
No server-free tape I/O unless some other "server" is driving it.


Allen S. Rout wrote:
Greetings, all.  I'm contemplating some upgrades to my TSM
infrastructure, and trying to determine where I think the bottleneck
will move.

I'm adding tape drives, and intend to do a huge load of reclamation
Real Soon Now.  So, my question is: Does tape-to-tape copy which the
TSM server deems "local" actually touch the server bus at all?  For
example; if I have 32 3592 drives (shush; let me dream), sufficient
SAN fabric to keep them all fed, and sufficient reclamation work to
keep them occupied, all totally devoted to reclamation:

Is my -server- doing I/O work, or just bookkeeping?

The tape IO management stuff (or lack thereof) leaves me feeling
adrift, when compared to the superb support for disk IO evaluation
I've grown to love out of NMON.  I feel like I understand my disk IO
intimately, but really wonder what's going on with the tapes.  I've
tried to work this out by calculating the 'negative space', but when
I'm doing lots of tape work, I'm also beating the snot out of my
database, so I'm not sure where to blame the IOWAIT.

Anyone got a clue to spare?


- Allen S. Rout

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