Why it is LTO2 capacity reads differently than 3590's. My 3590's report 40GB
when filling and "at least" 40GB when full. K tapes read 20/40 and LTO2's
200/400. So why wouldn't it show at least 400?

Is this a TSM, LTO or some other issue causing this?

Is a tape reporting 215GB when full really holding more than that?

It also makes no sense if estimated capacity is 400GB, and the drive is
capable of supporting that, it only reports 200.

Thanks,

Geoff Gill
TSM Administrator
PeopleSoft Sr. Systems Administrator
SAIC M/S-G1b
(858)826-4062
Email: geoffrey.l.gill AT saic DOT com



-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Troy Frank
Sent: Thursday, April 20, 2006 6:21 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: collocation groups

Here's what I'm guessing is happening with your tape utilization
numbers, as I've seen that here too.  Until the tape is actually full,
it seems to base it's %full on the "estimated capacity" of the device
class.  So I'm thinking you probably set your lto2 dev class to 400GB.
Once the tape is full, tsm switchs to stating the ACTUAL amount of data
it got on the tape.  The other peculiarity I noticed is that it doesn't
seem to take compression into account in that number.  To be honest it's
still a little confusing to me as well.  It seems to only show native
capacity (~200GB), but yet some tapes show a bit more  (~235GB), as if
it did take some compression into account.  That shouldn't be right
either though, as I know my data is more compressible than 17%.



>>> GEOFFREY.L.GILL AT SAIC DOT COM 4/19/2006 6:50 PM >>>
Question related to collocation groups:



If 10 nodes are in one group will it only mount one tape even if no
other
tape drives are busy?



If I have a directory disk pool that is cached will it still go to one
tape
after migration or will collocation groups affect that? What I see
leads me
to believe the answer is yes. I am seeing multiple tapes for the
directory
tape pool with little to no data. Do folks still use this option?



Why do tapes that are not full show capacity of 381GB yet when they go
full
only show about 200GB? Do I need to force compression on with the
drives or
something? (LTO2's, 3584 Lib)



Thanks,



Geoff Gill

TSM Administrator

PeopleSoft Sr. Systems Administrator

SAIC M/S-G1b

(858)826-4062

Email: < mailto:geoffrey.l.gill AT saic DOT com > geoffrey.l.gill AT saic DOT 
com


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