ADSM-L

Re: TSM and device block sizes

2000-05-29 01:21:26
Subject: Re: TSM and device block sizes
From: Phil Hosking <phil AT AE.IBM DOT COM>
Date: Mon, 29 May 2000 09:21:26 +0400
Richard-well actually I wasn't being entirely honest about the
documentation!  I read about the fixed blocksize in a PMR on RETAIN.
lsattr shows me block size of 0.  I can, of course change it, but what I
read indicates it gets ignored.  Here's the extract from the PMR:

      I have not yet heard from any one in the VTS support structure
yet, but have recieved feed back from my developers.
PAGE
.
51
      For a 3490 drive the maximum block that ADSM (or TSM for that
OF
matter) can write is 32,760 bytes. For a 3590 drive the maximum block
77
is 256kb. One new piece of information that I did not have before now
is, that to the best of her knowlege my developer says that the VTS
only shows itself to the outside applications as 3490 devices. And that
means that ADSM can ONLY send it 32,760 blocks. If the VTS can be
configured to represent a 3590 drive then the ADSM server could
feed it 256Kb blocks like it does to the 3570 library. I will pursue
this with the VTS folks when I hear from them. Does this match with
anything you have recieved from VTS support there in Germany ?

Phil Hosking       United Computer & Management Consultancy, P.O. Box 9226,
Dubai, U.A.E
     +9714 -3021502(direct)+971-50-6506941(mobile)+97143313312(fax)
phil AT ae.ibm DOT com


Richard Sims <rbs AT BU DOT EDU> on 05/29/2000 04:51:23 AM

Please respond to "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>

To:   ADSM-L AT VM.MARIST DOT EDU
cc:    (bcc: Philip Hosking/United Arab Emirates/IBM)
Subject:  Re: TSM and device block sizes




>It explicitly states that performance will be poor if you use
>small block sizes.  Now looking at the TSM documentation I see that TSM
>uses a block size of 32Kb and that it overrides what you set in AIX for
the
>drive itself.  Is this right?  Can I change the blocksize somewhere in
TSM?

Could you specify what TSM documentation you were looking at?
And what does an AIX 'lsattr' command on your system say that
TSM is actually using for tape drive blksize?
    Richard Sims, BU
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