Dan,

David already answered to question 2 but as an additional remark - when
TSM started to write a tape volume uncompressed the tape has to become
back scratch to start write on it with compression.

Zlatko Krastev
IT Consultant




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

Subject:        Re: baffling tape, 3584 HW compression, and stgpool design

For question 2, on my 3584 drives I have the FORMAT=ULTRIUMC and
it uses comperssion.  I'm getting about 275GB average on my tapes
(IBM tapes), have gotten nearly 400GB on some!

David Longo

>>> dsf AT GBLX DOT NET 08/27/02 04:34AM >>>
Couple unrelated questions:

1. When I query a 3570 library, there's one tape that baffles me:

adsm> q libvol 3570lib1

Library Name    Volume Name    Status               Last Use     Home
Element
------------    -----------    -----------------    --------- ------------
3570LIB1        133060         Private                           34

   I can't do anything with it -- ie, I can't discard the data on it
because
   ADSM says it doesn't belong to a storage pool, and yet, no indication
that
   it's a DbBackup. All other tapes in the library are sane and belongs to
   either scratch, a storage pool, or a dbbackup.

   So what could it be, and how do I wipe that lone offending tape and
change
   its status to scratch? (This is with ADSM 3.1+patches)

2. How do I enable hardware compression for LTO tapes? Some sort of device
   class or drive definition parameter? (This is with TSM 4.2.2+patches)

   I've looked through docs set and not finding anything that addresses
this.

   I'm currently using:

   tsm> DEFINE DEVCLASS 3584_DEVCLASS1 DEVTYPE=LTO FORMAT=DRIVE-
     MOUNTLIMIT=10 MOUNTWAIT=60 MOUNTRETENTION=0 LIBRARY=3584LIB1

   tsm> DEFINE DEVCLASS 3584_DEVCLASS2 DEVTYPE=LTO FORMAT=DRIVE-
     MOUNTLIMIT=2 MOUNTWAIT=60 MOUNTRETENTION=0 LIBRARY=3584LIB1

   The mountlimit of 10 and 2 is to put an hard upper bound on number
   of drives that the backups (10) and offsite copying (2) can use.

   The mountwait of 60 minutes is to avoid having jobs fail if they're
   sitting there, waiting for a particularly huge 300GB job to finish and
   free up a drive for it to use.

   Mountretention=0 is because this is a fast automated library (3584 with
   12 drives); I can see setting it to 10 or so if it was a smaller human
   operated library or requiring operator tape swaps like the 3570
library.

   3584LIB1 refers to the library, obviously. ;) (device /dev/smc0, etc)

   As I understand it, FORMAT=DRIVE means it uses the drive's compression
   settings. I haven't seen any explicit mention of what this defaults to
   nor how to adjust it in either the 3584 or TSM docs.

   Or would I use something like DEVTYPE=LTOC...?

3. Is there really a reason to use multiple storage pools for the same
   tape repository?

   Ie: the TSM 4.2 docs suggests an out-of-box default setup such as
DISKDIRS,
   DISKDATA that then migrates to TAPEDATA, which then copies to OFFDIRS
   and OFFDATA (offsite copy pool tapes). This makes sense. (I understand
the
   purpose for each and every one of them, and how they're organized.)

   Is there a good reason why someone might want to split up diskdata and
   tapedata into multiple stgpools? I ask because I've heard references to
   other folks having multiple stgpools, and wondering what I'm missing
here.

   That's the only thing I think that eludes my understanding in preparing
the
   new design, at this point.

Any insight or comments much appreciated. Thanks!

-Dan



"MMS <health-first.org>" made the following
 annotations on 08/27/2002 10:08:01 AM
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