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@xxxxxxxxxx [mailto:dm-devel-bounces@xxxxxxxxxx] On Behalf Of Romanowski, John (OFT) Sent: Thursday, November 29, 2007 6:12 PM To: device-mapper development Subject: RE: 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 -------------------------------------------------------- This e-mail, including any attachments, may be confidential, privileged or otherwise legally protected. It is intended only for the addressee. If you received this e-mail in error or from someone who was not authorized to send it to you, do not disseminate, copy or otherwise use this e-mail or its attachments. Please notify the sender immediately by reply e-mail and delete the e-mail from your system. -----Original Message----- From: dm-devel-bounces@xxxxxxxxxx on behalf of Stefan Bader Sent: Tue 11/27/2007 4:42 PM To: device-mapper development Subject: Re: 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@xxxxxxxxxxxxx>: > > 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@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
