FYI -
I have seen instances where 22MG per second is achieved..... although this
is very rare (all of the below implemented and low system utilization).
Rich's quote of 6-7 MPS is realistic for most environments.
A few tips to enhance performance (as appropriate for your
environment)........
1) Use a Fast/Wide Adapter
2) Keep one 1 device to an adapter (no daisy chaining)
3) Use hardware compresssion ( as opposed to SW or no compression)
4) Use the appropriate block size/buffer size
*Note: this is only applicable for NON-ADSM use of these devices. Why?
Because ADSM already has this "built in" to the code as it accesses the
device!
5) Use Faster Disks (these devices are faster than MOST disks can read)
6) Read data that is striped across an SSA Array
Always keep your microcode and device drivers current:
*Microcode can be obtained from 1-800-IBM-SERVE. Often, they will send it
to you with instructions for loading... other times they will come out and
do it for you.
Current Atape IS 4.1.7.0 available at ftp://208.222.234.135/devdrvr/AIX
*There are no SCSI parameters to change (especially with ADSM). The only
attributes that should be altered on the device characteristics are
COMPRESSION
or BLOCK SIZE (not needed for ADSM) or USE AUTOLOAD FEATURE AT END OF TAPE
(which should be NO for ADSM).
Be careful changing the COMPRESSION option midstream as you will have to
UPDATE DEVCLASS and change the FORMAT parameter. Also, once a tape has been
written to using one FORMAT, you can not write to it in a "new" FORMAT.
This includes even if only a label has been written (but no data).
Cheers -
Jennifer
At 05:08 PM 7/10/98 -0300, you wrote:
>Rich,
>thanks for your fast answer.
>
>Folks,
>
>The 3590 has a performance of 9MB/s in the foils, just in the foils. A good
>and real performance is 6.5MB/s. You have a performance of 4.2MB/s per drive
>(is the same that I have in my environment).
>The question is:
>How can I grow this performance (4.2MB/s ---> 6.5MB/s) ?
>
>The my performance, of course, with small files is worse than with big
>files. With you, is the same ?
>
>Thanks,
>Leandro.
>
>-----Original Message-----
>From: Lynch, Rich <Lynch.Rich AT mbco DOT com>
>To: 'Leandro Carneiro Torres' <ctorres AT serviceinf.com DOT br>
>Date: Sexta-feira, 10 de Julho de 1998 16:10
>Subject: RE: 3590 Tunning
>
>
>I backup SAP databases to 3590's in a 3494 at about 30 gig an hour, no
>client compression.
>I havent done any SCSI tuning, I have a total of 4 drives on two SCSI
>fast/wide channels, but I only use two tape drives for SAP backups at
>any one time, the other two are for ADSM space reclamation and copypool
>use. Make sure your at the latest level of Atape, I think its 4.1.7
>
>----------
>From: Leandro Carneiro Torres [SMTP:ctorres AT serviceinf.com DOT br]
>Sent: Friday, July 10, 1998 1:12 PM
>To: ADSM-L AT VM.MARIST DOT EDU
>Subject: 3590 Tunning
>
>Folks,
>are you have any triks to I get the best performance with ADSM
>Server for AIX v3.1.1.3, ADSM Client for AIX v3.1 and 3590 tapes ?
>What is the "Average Data Transfer Rate" that you get with small
>and big files in this environment ?
>Is true that exists SCSI parameters that I can change ?
>
>Thanks,
>Leandro.
>
>
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