Brian T. Huntley writes:
> Hi all....
>
> When we first implemented ADSM with a 3494 library, I had colocation
> off on all storage pools to use tapes as efficiently as possible.
>
> Although not an ideal solution, it was the best I could do when I was told
> I had 0 tape budget... but since then I've managed to convince the
> penny-pinchers that tapes should be in the budget as a consumable just
> like toner cartridges, paper, and pens, so I now have a little bit more
> ability to purchase more tapes.
>
> My question is this: Is there any way to calculate how many more tapes
> would be required if a non-colocated tape storage pool were migrated to a
> colocated one?
You do not need more tapes. If there are not enough empty/scratch tapes,
ADSM will still store several client's date on the same tape. The data will
nevertheless be collocated: new data arriving will go to a tape already
holding data of that client. Of course, the effect of collocation will be
better, if you spend more tapes. It's a simple tradeoff. You decide.
Our server has the tapes specifically defined to the storage pools and does
not use scratch tapes. This way we limit the number of tapes used. We
typically have 30 tapes in FILLING state (0 EMPTY tapes, of course) for
our 600 clients.
> Assuming I could purchase as many tapes as required, would
> it be worth my time (and the server's time) to do this?
Your time? It doesn't take much time to say "UPD STG poolname COLL=YES",
does it? If you switch collocation on, future data movements will be under
the collocation regime. Gradually, your data will become more and more
collocated. Of course, if you want your data to be collocated ASAP, you
will actually have to move the data, which costs your and your server's
time.
> We've had a lot of (relatively small) Novell and NT restores lately that
> have required 40 or more tape mounts, and taken several hours. Needless
> to say, this is getting rather annoying.
>
> Thanks much for your input!
>
> -
> Best regards,
> Brian
>
> +-----------------------------------------------------------------------+
> | Brian T. Huntley Systems and Network Engineer |
> | Campus Information Services, Clarkson University |
> | Ph/FAX: 315.268-2292/6570 |
> | bth AT clarkson DOT edu
> www.clarkson.edu/cis |
> +-----------------------------------------------------------------------+
> UNIX *is* user friendly. It's just selective about who its friends are.
> PGP Public Key available. finger bth AT clarkson DOT edu
--
Reinhard Mersch Westfaelische Wilhelms-Universitaet
Reinhard Mersch Westfaelische Wilhelms-Universitaet
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