ADSM-L

Re: [ADSM-L] disk question

2010-04-22 02:53:53
Subject: Re: [ADSM-L] disk question
From: Henrik Vahlstedt <shwl AT STATOIL DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Thu, 22 Apr 2010 08:52:03 +0200
Thanks for the answer Rick.

//Henrik

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT vm.marist DOT edu] On Behalf Of 
Richard Rhodes
Sent: den 21 april 2010 20:40
To: ADSM-L AT vm.marist DOT edu
Subject: Re: [ADSM-L] disk question

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
             >                                                          To
             Sent by: "ADSM:           ADSM-L AT VM.MARIST DOT EDU
             Dist Stor                                                  cc
             Manager"
             <[email protected]                                     Subject
             .EDU>                     disk question


             04/21/2010 11:11
             AM


             Please respond to
             "ADSM: Dist Stor
                 Manager"
             <[email protected]
                   .EDU>






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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