From: Stephane Dupuis (SDUPUIS@BOUYGUESTELECOM.FR)
Date: Thu Jun 05 2003 - 05:48:52 EDT
Hi,
I ask IBM a few days ago how to get the best performance with an ESS,
(fiber chanel/with SDD) and they answer me that LVM striping should'nt be
use.
They were thinking that we will have better berformance with "spreading"
(with the mklv -e x cmd).
I don't know exactly why... But It's maybe because of how the ESS work.
All luns on ESS are already striped, using 128k chunksize. So, maybe it's
not a good idea if the aix LVM also send 128k bloc of data.
It seams also that LVM striping can degrad performance of the prefetch
cache algorithme in the ESS.
Anyway, only real testing can show you what is the best for your
configuration.
-----Message d'origine-----
De: Bill Verzal [mailto:BVerzal@KOMATSUNA.COM]
Date: mercredi 4 juin 2003 18:12
À: aix-l@Princeton.EDU
Objet: Re: ESS config for single threaded throughput
Set stripe size to 64 or 128K. Then be sure to alternate ESS Clusters in
the allocations (first read from ESS cluster 1, second read from ESS
cluster 2, third read from ESS Cluster 1...)
Set vmtune -R to some number > 16. Set vmtune -f and -F accordingly.
A couple questions though...
- Will this be random or sequential I/O?
- Will it be SCSI or Fiber?
- What is the system type of the AIX box?
- What oslevel are you on?
- Are you using the SDD for load balancing and failover ?
These 5 questions will determine the next level of tuning.
BV
--------------------------------------------------------
Bill Verzal
AIX Administrator, Komatsu America
(847) 970-3726
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| To: aix-l@Princeton.EDU
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| Subject: ESS config for single threaded throughput
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I've got an IBM ESS in a sandbox environment. I'm interested in creating
a
file system with the best possible single threaded performance. So far
what
I've done is create sixteen logical volumes, and make them available to my
aix system. At this point would it make sense to create a filesystem that
stripes across these 16 volumes? What stripe size should I use? I'll be
reading data from the disk and sending it off to either /dev/null or a tape
drive that can compress the data on disk.
Can something similar be done in a Win2k environment to have a single
logical drive with high single streamed throughput?
James Thompson
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