[Veritas-bu] Expired Backup ID Doesn't Free Up Some Space

2010-09-29 08:45:22
Subject: [Veritas-bu] Expired Backup ID Doesn't Free Up Some Space
From: Mark Hickey <Mark.Hickey AT hds DOT com>
To: "veritas-bu AT mailman.eng.auburn DOT edu" <veritas-bu AT mailman.eng.auburn DOT edu>
Date: Wed, 29 Sep 2010 08:44:32 -0400

I knew someone would pull out some niche backup product from some tiny vendor to hit me in the head with….:-)


This is the last I thing I will add to the discussion, as it is a bit off-topic, but for my own curiosity…


Dean, are you talking about reclaim?  Because I don’t think that is exactly the same thing, though some might argue it is just semantics.  If I understand correctly, reclaim copies unexpired images off of partially full tapes onto partially full tapes to increase both the number of full tapes and the number of empty tapes based on a threshold of unexpired capacity.  


If this is what you are talking about, then while it may in the end support some of what Adrian is doing, it is not what I was referring to. I was saying that I don’t think any backup applications notice an expired image in the middle of a tape, mark the tape used by that image as available, and then write new images on that same space on that same tape.


Please help me understand TSM’s capabilities better if I am misinformed about this.




Dean wrote:


> IBM does tape recycling, and has for decades, first on the mainframe, and TSM is heavily based on the same concepts as HSM on the mainframe.

> They even called it "recycle".... F DFHSM,RECYCLE ALL P(30) EX


>It means you can mix up your retentions on a single piece of tape media, but it also means you have to dedicate a good proportion of your tape hardware/time to looking after the recycle process (ie - basically doing tape-to-tape copies every day to filter out the expired data).


> There are pros and cons.


> Sorry, I have nothing to add to what Mark has said, other than to call out his "no vendor does it" :)





Mark Hickey
Principal Technical Consultant
62 Beach Road
North Weymouth, MA 02191
O 781.331.3508
C 781.254.6441

mark.hickey AT hds DOT com 


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