ADSM-L

Why not use many cheaps disk as a PRIMARY stg?

2000-08-02 05:53:18
Subject: Why not use many cheaps disk as a PRIMARY stg?
From: Jochem van Hal <jvhal AT ALLSHARE DOT NL>
Date: Wed, 2 Aug 2000 11:53:18 +0200
(send again, msg was misplaced as a reply under another msg)

Hi,

Recently, we're trying to decide about the various ways in which TSM can be
set up. We need about 2Tb of primary pool space. For primary pool only , we
may either:

1) Get a big library, and a lot of tapes, amounts to >$50.000. (With the lib
we can also maintain the copy pool)

2) Get a bunch of IDE-disk cabinets, and a lot of 70 Gb IDE disks, amounts
to $25.000 or so (of course we will also need a small library for the copy
pool). These cabinets have a scsi interface.

It seems IDE disks are not only the cheaper, but also the much faster
solution for daily retrieve operations. In this case we would opt for a
RAID-5 IDE set for primary stg (but also a fast(er) SCSI system for the DB
and LOG). With this amount of disks some are bound to crash every now and
then, RAID-5 helps. All in all, the TSM server only 'sees' scsi.

One cabinet would show up like one disk, in reality 70Gb disk times 7 disks
= 0.5 Tb/cabinet, which is a rather big 'disk' size.

Question 1) However, on the forum no-one seems to use a PRimary IDE (PRIDE)
disk pool? Why? I'm i missing something or what?

Question 2) If PRIDE seems like a good solution, would the better way to use
DISK devices (any TSM limits?, caused by size or sheer number of DISK
volumes on the PRIDE disk) or FILE devices (but fragmenting files all over
the disks, and need of reclaim)

Question 3) Any (other) TSM limits endangering this plan (we are talking
about 2Tb or more on disk...)

Of course OS limits have been accounted for. It seems AIX and NT are OK.

Thank you,


Allshare Personnel BV
Jochem van Hal
TSM admin
jvhal AT allshare DOT nl
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