1. hundreds of clients can simultaneously back up to a disk pool.  Only four
clients can back up simultaneously to a library with four tape drives.

2. Tape drives perform horribly if they stop and start frequently.  If you
can stream the data to them fast enough to keep them busy ,they perform very
well.  One client going over a network cannot keep up with a tape drive, so
ithe drive stops and starts and perfomrs badly.  But weh nthe TSM server
migrates the disk pool to tape, it WILL feed the tape drive fast enough to
get good performance out of it.

3. If you cache your disk pool, next-day restores can come directly from
disk - much faster than tape.

Hope this helps.
---------------------------------
Mr. Lindsay Morris
Lead Architect, Servergraph
www.servergraph.com <http://www.servergraph.com>
859-253-8000 ofc
425-988-8478 fax


> -----Original Message-----
> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]On Behalf Of
> Conko, Steven
> Sent: Thursday, October 31, 2002 8:34 AM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Re: Multiple sessions per tape
>
>
> why does having the diskpool in between improve performance?
>
> -----Original Message-----
> From: Alexander Lazarevich [mailto:alazarev AT HERA.ITG.UIUC DOT EDU]
> Sent: Wednesday, October 30, 2002 4:35 PM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Re: Multiple sessions per tape
>
>
> Totally. We used to backup to tape. But since putting a disk spool
> inbetween, the performance has significantly improved.
>
> Alex
> ---                                                        ---
>    Alex Lazarevich | Systems | Imaging Technology Group
>    alazarev AT itg.uiuc DOT edu | (217)244-1565 | www.itg.uiuc.edu
> ---                                                        ---
>
>
> On Wed, 30 Oct 2002, Joshua Bassi wrote:
>
> > It is restricted to one.  The best way to backup your data is to a disk
> > pool first, then bleed the diskpool to tape and you will get much better
> > performance out of your single session than you would if you backed up
> > directly to tape.
> >
> >
> > --
> > Joshua S. Bassi
> > IBM Certified - AIX 4/5L, SAN, Shark
> > Tivoli Certified Consultant - ADSM/TSM
> > eServer Systems Expert -pSeries HACMP
> >
> > AIX, HACMP, Storage, TSM Consultant
> > Cell (831) 595-3962
> > jbassi AT ihwy DOT com
> >
> >
> > -----Original Message-----
> > From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On 
> > Behalf Of
> > Conko, Steven
> > Sent: Wednesday, October 30, 2002 10:16 AM
> > To: ADSM-L AT VM.MARIST DOT EDU
> > Subject: Multiple sessions per tape
> >
> > We're running ADSM 4.2 on AIX 4.3.3, 3494 library, 3590 drives.
> >
> > Is there any way to control the number of sessions per tape or is it
> > restricted to one?
> >
> > Steven A. Conko
> > Senior Unix Systems Administrator
> > ADT Security Services, Inc.
> >
>