List,
An addendum:
The client has now performed the change (it's been my first day back onsite
with them since working through the planning with them) and they report that
it all went swimmingly. From what I've seen there's now a happy co-existence
of LTO2 and LTO4 drives and LTO2 and LTO4 media within the same logical (IBM
3584) tape library - LTO2 media is getting mounted into LTO2 or LTO4 drives
for R/O activities, LTO2 media is getting mounted only into LTO2 drives for
R/W purposes, and LTO4 media is mounted only into LTO4 drives for R/W
operations. Simple operational procedures have been updated (e.g. an update
to their Q_SCRATCH script to returns how many scratch tapes there are of
each media type etc).
They may well be keeping some LTO2 drives and media in this configuration
for a while longer for generation of their offsite volumes – as long as the
capacity figures and support for this make sense, it means they’re not
having to shell out on a whole load more LTO4 media up front (which ‘aint
cheap) before they need to.
Thanks again to the list for your help in reassuring me that this should
(and does) indeed work well. I’ll report back in case I hear of anything
else on this.
David Mc
London, UK
From: David McClelland [mailto:david.mcclell...@networkc.co.uk]
Sent: 23 March 2009 18:06
To: 'Bill Smoldt'; 'ADSM: Dist Stor Manager'
Subject: RE: [ADSM-L] Fwd: [ADSM-L] Mixing LTO2 and LTO4 drives and media in
the same library
Hi Bill,
Many thanks for feeding back with this.
(Why do things like this always come through and scare me like that right at
the end of my day in the office just when I’m getting set to head home...!)
The APAR suggests 5.5.2.0 and 5.4.4.1 and above are currently affected by
this issue (and perhaps as a result of the IC54738 fix from my reading of
it) – it’s Windows TSM 5.4.3.2 onsite here now (migrating to AIX TSM
5.5.1.1), so I think they’ll just about dodge underneath this issue I
reckon.
The mixed LTO2/4 media/drives is a config they’ll be running for (to the
current plan) about 5 weeks before the wholesale migration to LTO4 drives
and read only LTO2 media.
Many thanks,
David Mc
London, UK
From: Bill Smoldt [mailto:smo...@storserver.com]
Sent: 23 March 2009 17:19
To: david.mcclell...@networkc.co.uk; ADSM: Dist Stor Manager
Subject: Re: [ADSM-L] Fwd: [ADSM-L] Mixing LTO2 and LTO4 drives and media in
the same library
David,
While I understand that this works in specific circumstances, we’ve had
significant problems with your specific combination. The problem we
observed will occur with a current release of TSM server and any two-level
gap in LTO generations and the right circumstances. You may want to wait on
implementation until you are running a TSM version which contains the fix
described in APAR IC59691. Unless you can live with that feature.
HYPERLINK
"http://www-01.ibm.com/support/docview.wss?uid=swg1IC59691"http://www-01.ibm
.com/support/docview.wss?uid=swg1IC59691
--
Bill Smoldt
VP Research & Development
STORServer, Inc.
719-266-8777 x7103
_
From: David McClelland
Reply-To:
Date: Fri, 20 Mar 2009 05:39:28 -0600
To:
Subject: Re: [ADSM-L] Fwd: [ADSM-L] Mixing LTO2 and LTO4 drives and media in
the same library
(War and Peace again - sorry):
Thanks for all of your responses both on and off list. I've put some feelers
out elsewhere on this too (many thanks if you're reading) and have had some
interesting and contradictory responses!
In summary, there do seem to be some folks out there running with exactly
the proposed config below (i.e. LTO2 and LTO4 drives and media in the same
logical/physical library, LTO2 used purely for offsite media generation)
and, provided parameters such as MOUNTLIMIT are set carefully (as well as
separate devclasses and stgpools of course), it is a happy configuration
without undesired LTO2 > LTO4 cross pollination.
The 'Implementing IBM Tape in Unix Systems' Redbook is an excellent read and
talks about this configuration in one of its examples (going against my
reading of the TSM Admin Guide):
"As of Tivoli Storage Manager V5.3.5, LTO4 drives are supported, and any
combination of LTO 2, 3, and 4 drives and media can be used in one library
[...] Although LTO4 drives can read the LTO2 media (but cannot write to it),
care should be taken to avoid attempted writing. Set the MOUNTLIMIT option
for the LTO2 devclass to less than the sum of LTO2 and 3 drives (see the
previous tip), thereby preventing the LTO2 media from being loaded in the
LTO4 drives. The LTO2 media will still be available for normal use by the
LTO2 [and 3] drives.
"['Previous tip' - relates to different scenario but the point is still
valid] Setting the MOUNTLIMIT parameter: For read or write tape mounts,
Tivoli Storage Manager will select LTO3 drives for LTO3 media first. If no
LTO3 devices are available, an available LTO4 drive will be selected for the
LTO3 media. To prevent the case where all LTO
