Firstly I must ask people to accept my apologisies if this message doesn't
look right.... This is first time I have tried to post a message hear :-)

Just reading through a scenario posted by Michael Wheelock about slow tape
to tape perforance... There are lots of considerations here to take note
of...

We run with an P660-6M1 (near enough a similar server) with a 3584 attached
to four HVD SCSI LTO Drives and four FC LTO Drives (over a SAN). Each SCSI
drive is attached directly to its own SCSI card in the server to max the
performance. With the FC drives we can see all four over each of the four FC
adapters in the server. You need to make sure you use the as few drives on
one FC bus as possible...

+ fcs1              51-08             FC Adapter
* fscsi1            51-08-01          FC SCSI I/O Controller Protocol
+ rmt8              51-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ rmt9              51-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ rmt10             51-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ rmt11             51-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ fcs2              61-08             FC Adapter
* fscsi2            61-08-01          FC SCSI I/O Controller Protocol
+ rmt12             61-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ rmt13             61-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ rmt14             61-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ rmt15             61-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ fcs3              71-08             FC Adapter
* fscsi3            71-08-01          FC SCSI I/O Controller Protocol
+ rmt16             71-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ rmt17             71-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ rmt18             71-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ rmt19             71-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ fcs0              21-08             FC Adapter
* fscsi0            21-08-01          FC SCSI I/O Controller Protocol
+ rmt4              21-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ rmt5              21-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ rmt6              21-08-01          IBM 3580 Ultrium Tape Drive (FCP)
+ rmt7              21-08-01          IBM 3580 Ultrium Tape Drive (FCP)

In the example above using one drive for my explaination rmt8, rmt12, rmt16
and rmt4 are the same physical drive seen across four FC paths. so in this
case I would pick rmt8. Second drive can be seen as rmt9, rmt13, rmt17 and
rmt5 so I use rmt13 and so on.

If you run like this then you are maxing the throughput available to each
drive.... Please note the IBM recommendation is no more than 2 drives per FC
adapter.

With the above configuration we achieve tape-to-tape of around 40-80GB an
hour (depending on data and client/server compression).

A couple of other tweaks we have set in dsmserv.opt

TXNGroupmax 256
MOVEBatchsize 1000
MOVESizethresh 5000

Finally on the devclass we have set the format to ultriumc.

Let me know how you get on....

Cheers

Andy Wilcox




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