Don't forget collocation by group.
All of our nodes belong to one group or another and we can then be pretty
sure that collocation will do what we need. Mostly, our tape pools are
collocated by group. Some nodes are in a group all by themselves and some
(e.g. workstations) have many nodes in their group. We only use collocation
by filespace if it is really needed for the largest nodes.
Bob
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Sam
Rawlins
Sent: Thursday, January 15, 2009 2:20 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] How to figure collocation overhead
Hi Bill,
I like Wanda's point. MAXSCRatch is the best way to control tape usage. You
can probably write a fun select to see how many nodes have data on the
average tape. In Wanda's example, there are about 2 nodes per tape. If you
see that that number gets too high, you can increase MAXSCRatch.
On Thu, Jan 15, 2009 at 11:53 AM, Wanda Prather
<wanda.prather AT jasi DOT com>wrote:
> Collocation consumes as much of the library as you tell it to.
>
> When you set MAXSCRATCH on a storage pool, TSM will confine the pool to
> that
> number of tapes. If you have less tapes available than you have clients,
> you get a "do the best you can" collocation.
>
> There are plenty of sites who have more clients than slots in their
> library.
>
> If you have 100 clients and set MAXSCRATCH for the pool to 50 tapes, TSM
> will put each client on a different tape until it hits 50, then it will
> double up.
>
> You still get a decent amount of collocation; it's a lot faster for a
> restore to skip over another clients data on the same tape, than it is to
> rewind, dismount, mount, and reposition to a different tape.
>
> What you have to remember if you are collocating, is that you have to
check
> your pools periodically and reevaluate maxscratch for the pool. If your
> total amount of data is growing, you will need to up the maxscratch
> periodically so that you maintain enough available free tapes in the pool
> to
> provide a reasonable level of collocation.
>
> W
>
> On Thu, Jan 15, 2009 at 1:34 PM, Evans, Bill <bevans AT fhcrc DOT org> wrote:
>
> > Is there a guide or rule of thumb for determining what collocation will
> > do to library space? It is being considered for improving restore
> > speeds.
> >
> > I'm backing up 80TB in 30 volumes(filespaces) on a solaris server.
> > Currently there is no collocation set, all data goes to a long-term
> > management class, single onsite and off-site tape pools, data churn
> > averages < 1TB/night.
> >
> > Using a 650 slot L700 library, LTO3, TSM 5.5, AIX 5.3. The library is
> > >80% full, so, I'm concerned that starting collocation for the volumes
> > will consume the rest of the library. Each filespace collocation may
> > end up with one tape not full (or 30 in this case).
> > Thanks,
> > Bill Evans
> > Research Computing Support
> > FRED HUTCHINSON CANCER RESEARCH CENTER
> >
>
--
Sam Rawlins
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