Re: Number of HBA's

"but why design to do that?"  For the very practical reason that money doesn't 
grow on trees.
If someone were to purchase and IBM 3584 with 12 LTO3 drives would we suggest 
that they use 12 HBA's or 6 dual port HBA's? In  most cases I think not.  There 
is a number of drives per HBA which should be met but it is more site and 
situation specific than a rule.  You should be aware of how fast the drives can 
stream but you should also know how fast you need them to go.  You should not 
under size your solution but you should also not oversize it either. Your point 
about database backup performance being dependent on disk speed.  This is yet 
another reason not to determine how many drives per HBA you use simply based on 
the speed of the drive.


Orville Lantto <orville.lantto AT DATATREND DOT COM> wrote:
The point was that two HBAs for tape only provides bandwidth for two tape
drives with compressible data, not four. Many people seem to under
appreciate the bandwidth requirements of a properly designed tape system.
For database data, it is usually the disk that is to slow to achieve
optimum backup speeds. Yes, you can run the tape drive at a slower speed,
but why design to do that?

Orville L. Lantto
Datatrend Technologies, Inc. (http://www.datatrend.com)
IBM Premier Business Partner
121 Cheshire Lane, Suite 700
Minnetonka, MN 55305
Email: Orville.Lantto AT datatrend DOT com


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"Loon, E.J. van - SPLXM"
Sent by: "ADSM: Dist Stor Manager"
02/09/2005 02:13 AM
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Re: Number of HBA's






Hi Orville!
I don't think this is really necessary since LTO2. LTO1 performance does
suffer when you can't keep the drive streaming, but LTO2 and 3 adjust
their
tape speed if they detect that the amount of incoming data is too low. So
there should not be any back-hitching here...
Kindest regards,
Eric van Loon
KLM Royal Dutch Airlines


-----Original Message-----
From: Orville Lantto [mailto:orville.lantto AT DATATREND DOT COM]
Sent: Tuesday, February 08, 2005 21:33
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Number of HBA's


Don't forget drive compression when making throughput calculations! 80
MB/sec * 4 (compression of text data) =320 MB/second as the maximum
available bandwidth per LTO-3 drive.

Good Luck keeping ONE of these beasts streaming with high compression!



Orville L. Lantto
Datatrend Technologies, Inc. (http://www.datatrend.com)
IBM Premier Business Partner
121 Cheshire Lane, Suite 700
Minnetonka, MN 55305
Email: Orville.Lantto AT datatrend DOT com

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Ben Bullock
Sent by: "ADSM: Dist Stor Manager"
02/08/2005 02:10 PM
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Re: Number of HBA's






The documents say you are supposed to NOT have SAN and
tape
devices running on the same HBAs.

I would expect you would use 2 HBAs to connect to the SAN
and 2
to connect to the tape drives. 2 cards have more than enough bandwidth
to support the 4 LTO3 drives.

Ben


-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Stef Coene
Sent: Tuesday, February 08, 2005 1:03 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Number of HBA's

Hi,

For a setup with:
- 4 x LTO3 drives in a IBM 3583 library
- 1 oracle database server: 40GB/1hr archives that needs to backuped
(AIX
LPAR) over the SAN
- 1 TSM server (AIX LPAR)

What with the HBA's? Is it needed to split the tape and disk activity
and to put 4 HBA's in the oracle DB (2 HBA's for disk activitiy and 2
for tape)?

Idem for the TSM server. 2 HBA's or 4 HBA's?


Stef


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