Re: Slow tape to tape performance

FYI. Quoted from the Admin Ref:
"MOVESizethresh megabytes
Parameters
megabytes
Specifies the number of megabytes as an integer from 1 to 2048. "

Zlatko Krastev
IT Consultant

"Wilcox, Andy" <andy.wilcox AT AQUILA-NETWORKS.CO DOT UK>
Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
27.12.2002 13:46
Please respond to "ADSM: Dist Stor Manager"

To: ADSM-L AT VM.MARIST DOT EDU
cc:
Subject: Re: Slow tape to tape performance

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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