I do something like this, but what I do in a script is, if the
reclamation threshold is not 100, and there is no offsite reclamation
process running, I lower the reclamaiton threshold by 1. I also have a
lower limit in the script.
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On Thu, 27 Mar 2003, Coats, Jack wrote:
> I had similar issues. I found that if I did some reclamations each day,
> and do something like reclaim 85% on Monday, Tuesday 80%, Wed 75% etc,
> that it works pretty well over time than doing something like 50% every day,
> even if that is your target.
>
> Why does this work? Basically it forces the 'most empty' tapes to be
> recovered first.
>
> Why does it choose the files it does? This is a question for some TSM
> internals
> expert, but IMHO, if I was coding it, I would probably
> 1. find the eligible tapes to reclaim in the selected storage pool
> 2. on those tapes, list all the remaining files,
> 3. sort the list of these remaining files by the tape they reside on
> in
> the local storage pool,
> 4. find the local tape with the most files on it I need to move
> 5. process that tape
> 6. restart a 1 above
>
> If there is a TSM Internals guy, is that similar to what is done? Just
> curious.
>
> -----Original Message-----
> From: Matt Simpson [mailto:matt AT UKY DOT EDU]
> Sent: Thursday, March 27, 2003 8:52 AM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Offsite reclamation questions
>
>
> When a reclaim process starts for offsite tapes, and I have a bunch
> of tapes that are within the threshold, does anybody know how TSM
> decides which volumes or files to reclaim first? When the
> reclamation process starts, I see a whole bunch of messages like
>
> ANR1040I Space reclamation started for volume 500394, storage pool
> BACKUPOFFSITE (process number 1514).
>
> apparently for every tape which meets the threshold. Is it going to
> reclaim all the files for one volume before moving on to the next?
> Or is it just going to start reclaiming all files on all those
> volumes in some arbitrary sequence?
>
> The reason I care is that if we have limited time for reclamation and
> can't reclaim all the eligible volumes within that window, I'd
> obviously rather reclaim all the files from a few tapes and get those
> tapes back than reclaim some files from a bunch of tapes and get none
> of them fully reclaimed.
>
> Ideally, I'd like to see TSM start with the volumes with the highest
> reclaimable space, which can be reclaimed most quickly. If it's not
> going to do that, I might want to force it by setting the reclaim
> threshold higher.
>
> We're using LTO tapes for our offsite copy pools. We're currently
> setting the threshold at 50%, and I'm wondering if that's too low,
> since that requires moving 100 GB to reclaim one tape. If I set it
> higher, less data movement is required, but the tradeoff is that we
> end up with more partially filled tapes in our vault. I'm starting
> to think that's a reasonable tradeoff, since the lower threshold
> might actually mean we have less chance to get any tapes fully
> reclaimed.
>
> Any thoughts?
>
>
> --
>
>
> Matt Simpson -- OS/390 Support
> 219 McVey Hall -- (859) 257-2900 x300
> University Of Kentucky, Lexington, KY 40506
> <mailto:matt AT uky DOT edu>
> mainframe -- An obsolete device still used by thousands of obsolete
> companies serving billions of obsolete customers and making huge obsolete
> profits for their obsolete shareholders. And this year's run twice as fast
> as last year's.
>
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