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"Paul Cote" 11-29-2007 10:33 PM

performance considerations with IO schedulers andDMmultipathing
 
John,

Interesting and thanks. Our customer will be doing throughput intensive
I/O (both reads and writes) ... So your observation may indeed be
helpful (deadline-25).

Paul

-----Original Message-----
From: dm-devel-bounces@redhat.com [mailto:dm-devel-bounces@redhat.com]
On Behalf Of Romanowski, John (OFT)
Sent: Thursday, November 29, 2007 6:12 PM
To: device-mapper development
Subject: RE: [dm-devel] performance considerations with IO schedulers
andDMmultipathing


Here's some links:

Google cache of this article:
"The basis for my test was to determine the best possible performance
combination of elevator tuning AND /etc/multipath.conf rr_min_io
setting."
http://72.14.209.104/search?q=cache:q2p5HOwGxHwJ:www.techyblog.com/conte
nt/view/45/28/+Multipath+rr_min_io+Oracle+Elevator+Benchmarks&hl =en&ct=c
lnk&cd=1&gl=us

"The short summary of our study indicates that there is no SINGLE answer
to which I/O scheduler is best."
http://www.redhat.com/magazine/008jun05/features/schedulers/

Oracle and linux I/O Scheduler
part 1- http://www.nextre.it/oracledocs/ioscheduler_01.html
part 2- http://www.nextre.it/oracledocs/ioscheduler_02.html
part 3- http://www.nextre.it/oracledocs/ioscheduler_03.html


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-----Original Message-----

From: dm-devel-bounces@redhat.com on behalf of Stefan Bader
Sent: Tue 11/27/2007 4:42 PM
To: device-mapper development
Subject: Re: [dm-devel] performance considerations with IO schedulers
and DMmultipathing

Hi Paul,

the device-mapper target itself doe not use any queue and so there is no
scheduler used at all. Only the real devices that are used as paths will
be using a scheduler. Whether there might be a performance gain by
changing these, I do not know.

Stefan

2007/11/27, Paul Cote <paul.cote@incipient.com>:
>
> Hi,
>
> Is there any advantage to one specific IO scheduler (below) that may
> improve IO performance / throughput when running with a round-robin
> failover policy? Has anyone done testing with this ... and willing to
> share results?
>
> thanks,
> Paul
>
> Completely Fair Queuing-elevator=cfq (default)
> Deadline-elevator=deadline NOOP-elevator=noop
> Anticipatory-elevator=as
>
>
>
> --
> dm-devel mailing list
> dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
>


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