On Thu, 20 Jul 1995 18:02:03 +0100 Heiko Andresen said:
>Hi ADSM'ers
>
>at the moment we're running an ADSM-Server on a RS6000/HACMP-Cluster with a
>10 GByte (brutto) RAID-Array and an EXABYTE 10e as Storage-Devices. Due to
>increasing Backup-activities and the missing dual-host attach of the
>EXABYTE-Lib I need to think about a new tape-box. My IBM-personnell
>recommended two alternatives: A 7331-205 (8mm Jukebox with two tape-devices
>and 20 tape-slots up to 280 GByte capacity) and a Magstar 3590-B11 with ten
>3490-tapes with a capacity up to 300 GByte. Now my questions:
>
>- What technology is better ? 8mm or 1/2 inch
1/2 inch. faster, more reliable, longer lasting media.
>- Do you have any expirience with these boxes ?
8mm yes, 3590 no (not yet). We do have experience with 3480/3490, but not
on ADSM.
>- What about reclamation, do I really need two drives (should work with the
> 7331-205, shouldn't it) ?
We have a LAGO datawheel, also a 2 drive robot. Only thing you have to
worry about is when the server does a RECLAIM (or you do a MOVE DATA). At
that time, user file recoveries can be delayed (for hours), because 8mm is
relatively slow compared to its capacity. It takes many hours (4-5?) to
empty a full 8mm tape. We implemented a Rexx exec to help us out with this
by cancelling the MOVE DATA or RECLAIM, if a user session is in Media Wait,
so that the user doesn't have to wait too long for this to finish. If it
was a MOVE DATA, the Rexx exec will later re-start it. If it was a RECLAIM,
then ADSM will re-start it automatically.
>- Any other suggestions ?
If you can afford it, I'd recommend going with the 3590 solution, even tho
we don't have any first-hand experience with it. The only salient feature
of 8mm, is that it is relatively much less expensive for that amount of
storage. However, it is fragile media. You must take care, especially
for archive data which has only 1 copy on tape, not to leave 8mm tapes in
the robot too long, or else they will wear out and you will lose data.
The relevance of this issue will depend on your particular situation and
how much you will end up mounting 8mm tapes. ADSM does keep track of tape
mounts per volume, so you can use those numbers to decide when to replace
tapes. We used to replace at 1000 mounts, but we recently lowered that to
300 mounts.
>
>Thanks in advance ...
Hope it helps.
>
>Heiko
>--
> *** Heiko Andresen Internet: andresen AT dresdnerbank DOT de
> ** ** Dresdner Bank AG Voice: ++49 69 263 10276
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