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" :)
Cheers,
Dean
On Wed, Sep 29, 2010 at 3:40 AM, Mark Hickey <Mark.Hickey AT hds DOT com> wrote:
> Adrian,
>
> Your problem , especially in the =case of physical tape, is that you put
> multiple retentions on the sane tape. I understand that in the short term
> this might reduce an initial tape purchase, but in the long term, you
> probably end up buying more tapes because the ones you are using contain 50%
> (or more) expired images, and at least one image that has not expired.
> Since it is very complex to try to “recycle” part of a tape cartridge, I
> don’t think any vendor does it.
>
>
>
> You have two basic options here:
>
> 1. turn of “Allow multiple retentions per tape” an create separate
> tape pools for policies with different retentions to pull from
>
> 2. Suspend the tapes from each backup session until all the images
> have expired.
>
>
>
> Mark
>
>
>
> Mark Hickey
> Principal Technical Consultant
> HITACHI DATA SYSTEMS
> 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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