The problem you'd have by going to multiple pools is that your single drives 
would be stuck with one pool anyway, and any overnight backups to the jukebox 
would have to wait for other clients to finish in order to change the tape so 
that they can use the one for their own pool.  If you get a hung saveset on the 
first jukebox backup, you don't get any further jukebox backups that night as 
the tape will not be ejected and you have no spare capacity to load tapes for 
other pools.
 
My personal preference is to keep pools as simple as possible and base this on 
retention policy.  One pool for each retention period (and keep as few as 
reasonably possible) and one for indexes and bootstrap.
 
If you're specifically looking at improving recovery times, I'd recommend 
getting a similar but seperate jukebox to clone to, preferably one which is 
based offsite (put it in a shed with power & a fibre connection out the back of 
the office).  If you're looking at using all your drives to recover 3 systems 
at once, it's because you've had a site based failure, and the benefit of 
cloning in this way is that you have easily accessible offsite (or "out of 
office" with my shed suggestion) backups which are also based on saveset rather 
than tape.  ie, you have one continuous saveset on tape which can just be 
streamed back to the server.  You *can* do this to different tapes on a server 
by server basis, but that's scripted wizardry rather than default option.  
 
In this case, I'd rather make sure you get the backups and know that recoveries 
will happen eventually rather than run the risk of not getting backups but 
having great recovery times when you do.
 
Cheers,
 
Stuart.

________________________________

From: EMC NetWorker discussion on behalf of Ben Harner
Sent: Thu 21-Sep-06 19:46
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: Re: [Networker] Backup Pools



Well first we have a IBM LTO 3581 jukebox and a IBM LTO 3580 single
drive.  We 1000 mbps throughput.  But the backup server only has a
100mbps card.   There are 17 clients.  At full backups 5 clients are at
least 100gb - 200gb per client.  And the others are between 30 and 60
gb.  5 groups are single client and are the larger clients, 1 is double
client median in size and 1 group has 9 clients which are smaller save
sets.  15 clients are using the jukebox and 2 are using the single
drive.  We have another single drive but that is used by a different
department but would be accessible to us in a disaster recovery
operation if need be which is why I was looking into breaking up are
most important server into different pools as to aid in a quicker
recovery.  If more than one server was to crash we could recover 3
servers simultaneously if we know for sure that the servers are on
different tapes.

Thanks for the help

Ben

Stan Horwitz wrote:
> On Sep 21, 2006, at 1:50 PM - 9/21/06, Ben Harner wrote:
>
>> Thanks for the reply.  So if I have a jukebox with 7 slots and say I
>> have 4 different pools with 1 to 2  tapes for each pool  you think
>> there would be long waits between backups?  Shouldn't it be only the
>> wait of the jukebox changing the tape?  Right now all session have to
>> wait for the previous one to finish per tape drive so wouldn't that
>> be the same either way?  Right now I have 15 clients being backed up
>> nightly to one tape drive using one pool.  I am trying to get it so I
>> can specify certain tapes for certain clients.  I'm guessing the only
>> way to do that is through pools.  Is there other ways?
>
> Possibly. Its difficult to say without knowing how much data would go
> to the individual devices and how fast the throughput is. Answering
> your question would be easier if you explained what your hardware and
> network environment is like and the amounts of data involved.
>
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