Hi Richard!
>The question is whether file type volumes do something like this also?
>Can TSM open
>directly to a desired file on a file type volume?
Can't answer this one, I haven't been able to try it myself, but I know
other (smaller) TSM shops do it. Guys? :-)
> VTL itself is a computer with a filesystem - doesn't it have the same
> problem? If the
> VTL appliance/head crashes would it not have to possibly fsck +100tb? I
> may not
> want to manage this directly on AIX, but the VTL has the same issue.
Probably true, but I think that the chance of crashing a DL700 is much
smaller than a crashing TSM server. We probably all encountered more than
one TSM crash, especially when running 5.3.0.0...
> If we use file devices we have to turn on client complression on all
> servers. Currently,
> we don't use client compression on most hosts, and get about a 1.5-to-1
> ratio from the
> tape drives. We're not sure many/most of our Windows and Netware servers
> have the power to perform client compression.
We were also a little bit hesitant to enable client compression. You cannot
predict the impact on CPU utilization and thus the impact on online
applications running on the client.
> 4) At the recent EMC technical conference at a presentation about their
> CDL, they
> recommended that colocation be TURNED OFF. They said that the speed of
the
> mounts and seeks made colocation unnecessary. I would assume this also
> with
> file devices, but it again depends upon the speed of seeking to a file in
a
> file type volume.
Indeed, we will implement a non-collocated pool on the DL700. Because you do
not use collocation, there will be less tapes in a filling state and a
better volume utilization. You can define a volume size for the virtual LTO2
tapes, so we will start with a 50 GB. volume. A larger volume will waist
space (with a reclaim percentage of 60%, the amount of expired data (40%)
will be much larger) and the risk of volume contention during multiple
restores will also be larger.
> 5) We just met with our local IBM TSM expert (very good guy!) about some
> things with
> our environment, and this topic came up. Interestingly, he even
> recommended possibly
> using disk type devices for backup-to-disk. This was a big surprise! I
> thought it was
>mostly agreed that only file type devices should be used.
Not true! A disk type storage pool doesn't allow you to reclaim aggregates,
which will result in a heavily fragmented diskpool in time.
Kindest regards,
Eric van Loon
KLM Royal Dutch Airlines
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