ADSM-L

Re: [ADSM-L] disk question

2010-04-21 14:44:28
Subject: Re: [ADSM-L] disk question
From: Richard Rhodes <rrhodes AT FIRSTENERGYCORP DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Wed, 21 Apr 2010 14:40:29 -0400
I can tell you my understanding - right or wrong!

Operating systems keep lots of I/O queues . . at least these:
- a queue for each HBA.
- a queue for each LUN.

By spreading your db across multiple luns and hba's, you can get more
parallelism - assuming your application can make use of the parallelism.
This is why TSM also should have it's database defined using multiple
volumes.  So you get multiple db vols across multiple lun's across multiple
HBA's.

Will it help?    It all depeneds . . .

The best thing I have ever read about this topic is the following.  It
doesn't specifically address your question, but it goes into a deep dive
about queuing.
http://virtualgeek.typepad.com/virtual_geek/2009/06/vmware-io-queues-micro-bursting-and-multipathing.html

Rick





                                                                       
             Henrik Vahlstedt                                          
             <shwl AT STATOIL DOT COM                                         
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Hi,

Are there any performance benefits in creating two or more LUN´s in the
same RAID group for one RHEL 5, TSM 5.5 database, instead of only creating
one LUN. If yes, why?
Example: IBM Midrange System Storage Implementation and Best Practices
Guide sg246363, see chapter 7.4/TSM database.

//Henrik


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