ADSM-L

Re: 3 layer storage hierarchy

2006-10-16 15:57:56
Subject: Re: 3 layer storage hierarchy
From: Andrew Raibeck <storman AT US.IBM DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Mon, 16 Oct 2006 13:54:58 -0600
Sorry folks, I misremembered... the scenario I am thinking of is described 
by APAR IC33719. The Admin Reference also contains this info for the 
NEXTSTGPOOL parameter in the DEFINE STGPOOL info for sequential access 
pools.

--------------------------------------------------
Specifies a primary storage pool to which files are migrated. You cannot 
migrate data from a sequential access storage pool to a random access 
storage pool. This parameter is optional.

If this storage pool does not have a next storage pool, the server cannot 
migrate files from this storage pool and cannot store files that exceed 
the maximum size for this storage pool in another storage pool.

When there is insufficient space available in the current storage pool, 
the NEXTSTGPOOL parameter for sequential access storage pools does not 
allow data to be stored into the next pool. In this case the server issues 
a message and the transaction fails.

For next storage pools with a device type of FILE, the server performs a 
preliminary check to determine whether sufficient space is available. If 
space is not available, the server skips to the next storage pool in the 
hierarchy. If space is available, the server attempts to store data in 
that pool. However, it is possible that the storage operation could fail 
because, at the time the actual storage operation is attempted, the space 
is no longer available.
--------------------------------------------------

TSM should do up-front space checks, and traverse as many "next" storage 
pools as needed to find a target storage pool. But once TSM starts to 
actually store the data in that pool, an out-of-space condition in that 
pool could cause the operation to fail.

Regards,

Andy

Andy Raibeck
IBM Software Group
Tivoli Storage Manager Client Development
Internal Notes e-mail: Andrew Raibeck/Tucson/IBM@IBMUS
Internet e-mail: storman AT us.ibm DOT com

IBM Tivoli Storage Manager support web page: 
http://www.ibm.com/software/sysmgmt/products/support/IBMTivoliStorageManager.html


The only dumb question is the one that goes unasked.
The command line is your friend.
"Good enough" is the enemy of excellence.

"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> wrote on 10/14/2006 
06:50:05 AM:

> We have customers that use the 3 layer pool. We set a maxsize on 
> both the disk pool and file pool.  I have one we just implmented 
> where we have a 500 GB disk pool with a maxsize of 50, then we have 
> a FILEPOOL1 with max size of 1 GB.  When our large Exchange database
> backups kick off they skip over both pools and request a tape mount.
> Further we've had times where migration kicks off and runs and our 
> backups still don't fail.
> 
>   Andy, is the situation you address one where the DISKPOOL and 
> FILEPOOL1 must fill up completly and aggregates won't move to the next 
pool?
> 
>   I just bring up the question because I believe if you lay out your
> disk and file pool with the right max size and migration threshholds
> this won't be an issue.
> 
>   K
> 
> Andrew Raibeck <storman AT US.IBM DOT COM> wrote:
>   Hi Remco,
> 
> Your observations are correct. If the target storage pool (DISKPOOL)
> cannot fulfill the request, then we'll try the next storage pool
> (FILEPOOL). But if the second request cannot be fulfilled, then TSM does
> not take it any further. This is a limitation that we are aware of, but 
at
> this time there are no plans to address it.
> 
> Best regards,
> 
> Andy
> 
> Andy Raibeck
> IBM Software Group
> Tivoli Storage Manager Client Development
> Internal Notes e-mail: Andrew Raibeck/Tucson/IBM@IBMUS
> Internet e-mail: storman AT us.ibm DOT com
> 
> IBM Tivoli Storage Manager support web page:
> http://www.ibm.
> com/software/sysmgmt/products/support/IBMTivoliStorageManager.html
> 
> The only dumb question is the one that goes unasked.
> The command line is your friend.
> "Good enough" is the enemy of excellence.
> 
> "ADSM: Dist Stor Manager" wrote on 10/13/2006
> 02:17:58 PM:
> 
> > Hi all,
> >
> > I've been playing with a 3 layer storage hierarchy; random access 
disk,
> > sequential disk (file) and finally tape.
> > Or more visual:
> >
> > DISKPOOL (maxsize 2G)
> > |
> > +---> FILEPOOL (no maxsize)
> > |
> > +---> TAPEPOOL
> >
> > Now, I've noticed that when the diskpool is full, or maxsize is
> > exceeded, clients will backup to filepool as expected. But they will
> > never fall through to tape, even if the filesize is over 2G and the
> > filepool is full, or both diskpool and filepool are full.
> >
> > Yes, there are plenty available scratch tapes, nor is maxscratch
> > exceeded on the tapepool. I've assigned about 80 volumes to filepool, 
no
> > scratch volumes. This all is on TSM 5.3.3.1 on AIX, but I've noticed
> > this on earlier versions as well.
> >
> > --
> > Met vriendelijke groeten,
> >
> > Remco Post
> >
> > SARA - Reken- en Netwerkdiensten http://www.sara.nl
> > High Performance Computing Tel. +31 20 592 3000 Fax. +31 20 668 3167
> > PGP Key fingerprint = 6367 DFE9 5CBC 0737 7D16 B3F6 048A 02BF DC93 
94EC
> >
> > "I really didn't foresee the Internet. But then, neither did the
> > computer industry. Not that that tells us very much of course - the
> > computer industry didn't even foresee that the century was going to
> > end." -- Douglas Adams
> 
> 
> 
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