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Difference between revisions of "Configuration Considerations (ESX)"
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Configuration Considerations (ESX) (view source)
Revision as of 14:23, 13 March 2012
, 14:23, 13 March 2012→Path Selection Policy (PSP): Added "Round Robin IOPS Load Balancing"
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| Round Robin (VMW_PSP_RR) || All || ESX uses all available paths (will be limited by AP arrays) | | Round Robin (VMW_PSP_RR) || All || ESX uses all available paths (will be limited by AP arrays) | ||
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=== Round Robin IOPS Load Balancing === | |||
The number of IOs that an ESX will use a path for, before switching to an alternate path to balance the load (so IOPS means ''IO operations'' in this instance rather than ''IOs per second'' as it normally means). | |||
Whether or not to change this is a contentious issue, the out of the box default is 1000. HP state that when using their EVA storage systems you should set IOPS to 1, and some other vendors appear to use IOPS=1 in their own testing (eg EMC). | |||
My personal feeling is to never change any setting from the default unless you have good reason to. The more you change, the more you move away from an expected configuration, and the more chance you have of exposing unexpected flaws and bugs, and the less chance a VMware support guy or gal will have of helping your resolve a problem quickly. | |||
I'm not convinced that the results show a significant improvement in performance by changing the value, and where there is, you need to remember that these are isolated tests, increasing the rate of path switching increases ESX CPU usage, so will be at the detriment of other performance metrics. So would I would not change as a default, but if you are experiencing performance problems its worth considering | |||
Some further reading... | |||
* http://virtualgeek.typepad.com/virtual_geek/2010/03/understanding-more-about-nmp-rr-and-iooperationslimit1.html | |||
* http://www.yellow-bricks.com/2010/03/30/whats-the-point-of-setting-iops1/ | |||
* http://vstorage.wordpress.com/2010/04/15/more-p4000-g2-benchmarking-with-roundrobin-tweak/ | |||
[[Category:ESX]] | [[Category:ESX]] | ||