On Thu, 15 Aug 2002 15:08:22 -0400, Jody Gregersen
<Jody.Gregersen AT VISHAY DOT COM> wrote:

>Hi,
>
>Does anyone have any information on how best to set up target sessions?
>
>We have a Compaq ES40 running networker 6.1.1 saving to a Compaq ESL9326
>storage array with 8 drives.  We have one backup that is ~375G and takes a
>long time.  The parallelism is set to 16.  Yesterday, I changed the target
>sessions on each drive to 16 from 12.  It seems that *all* the backups are
>taking much longer now.  In the manual, it says that in most cases writes
>are faster when they are all going to one tape so I don't understand the
>hold up.

Increasing the Target Sessions has resulted in ALL traffic being allowed to
go to ONE tape drive, instead of splitting some to second drive.  Target
Sessions now = 16, Server Parallelism = 16, therefore all savestreams will
end up on first drive, no others required.

Important note:  Target Sessions is not a hard limit - it is more
like "suggestion" - best used for load balancing across tape drives.  i.e.
savestreams will be sent to first drive until #TargSess is reached, then
start sending to next drive, etc. until all drives are used, at which point
they will round-robin.

So, moral of story is, for Targ Sessions, less works better in general.

I would recommend first lowering Targ Sessions to something like 4.  Then
consider increasing Serv Parallelism if you have NETWORK BANDWIDTH to drive
all drives.  Potential to drasticly reduce your overall backup time.

HTH
Carl Farnsworth
DigiDyne Inc.

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