On Fri, Aug 11, 2006 at 09:29:26AM -0400, Allen S. Rout wrote:
> Said from another direction, TSM doesn't worry about selecting only
> backed-up data from a stgpool when it's migrating, it takes whatever
> is there.
Thanks for the clarification.
> > Best practice-wise, do you try to define different private groups
> > and tape labels for onsite, archive and offsite storage? Or do
>
> Your recordkeeping problem is too complex to do by casual inspection,
...
> You will inevitably end up needing more "Primary" tapes when all
> you've got on hand will be labeled for "Reverse thudpucker" use or
> some such; Then you'll cross your own lines, and after the first time
> it gets easier and easier....
I've been running purposedly labeled tapes/pools for quite a while in
the leveled backup world of Networker. Jumping to a 'just the system
pick it' mentality is one of the hurdles (and appeals) of TSM. I fully
understand your point on the media labels, and will learn to live with
it. :)
> Having an extra drive outside a library isn't exactly a _bad_ idea,
> but unless you're trying to write a different format I'd expect you to
> get more value out of adding it to the library.
I don't think I can convert an external drive to run in the library.
You make good arguments for having internal drives, and I don't
disagree. But given that I have an external tape drive, it shouldn't be
an either/or for me to use it or the library.
> If you really, really want to do this, I'd suggest:
>
> - Define all of the drives to be "in" the library. set the one which
> is physically outside to usually be offline.
>
> - When you want to use the external drive, set the interior drives
> offline, the exterior online. Run the job, mount, dismount, etc.
>
> - When you're done, re-set to normal operations.
I suspect that by itself wouldn't work because the SCSI library would
want to do something to checkin/mount the drive, and I wouldn't want to
reconfigure switching the library to manual or not.
I'm thinking more along the lines of defining the SCSI library and
manual library, and switching the devclass between them as needed.
That's just a stopgap - it doesn't really make it usable, unless I
define an entirely new devclass and use it for relatively few things
(like backupsets or db backups to tape.)
No one else has dealt with transitioning between both manual and
automatic libraries?
> Personally, I'd much prefer checkin and checkout of desired volumes to
> this. And get a quote on how much the next bigger step of library is,
> and count the amount of time you spend screwing around with inadequate
> library space. That way you can demonstrate to the folks who are
> hoarding the beans when they start losing money because they didn't
> cough up a library at the outset.
>
> TSM is tremendously economical with tape and drive resources compared
> to other backup products. Feed it well; feed it hardware instead of
> your time.
That point is muddied when a drive configuration that worked just fine
with other backup products is either unusable or inadequate for TSM.
I'm sticking with my current hardware/specs for this first year and have
already warned the bean counters that odds are I'll need something near
the start of year two -- be it more drives, more library space, more
staging disk, beefier or multiple servers, etc.
> Now, if you were me, you'd try to develop a theory of copystg
> utilization workflow, and solve it for a minimum. But I suggest you
> just twirl the knob to the other end, and see if you like that
> tradeoff better.
Good point. I'll try some variations and see how it goes.
> You should consider data which has expired to be Gone, except for
> heroic measures.
>
> If you Really Need data which expired out of the database in the last
> week or so (a common period for retention of DB backups) then yes, you
> can do a complete DR scenario, and consult the as-yet unreused tape
> volumes for the data. Icky squicky.
Thanks, that's the definition I was looking for. As for "Really Need,"
it depends who asks... :)
> It's usually an answer like 'You messed this up last month, overwrote
> it every week and didn't notice until the first of this month, and
> have waited until NOW to ask me to get it back? No, it's gone.".
My backups will probably be augmented with regular archives (or
backupsets) for the important systems, so the provision of 'losing'
anything (at least for the people who "Really Need" it) should be pretty
low.
Any opinion on archives vs. backupsets for a monthly snapshot kept for 6
months?
Thanks for humoring me,
Dave
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