While changing this value from 1,000 to 1 can improve performance, it generally will not solve a major performance problem. While this is true in certain cases, the performance impact of changing this value is not usually profound (generally in the single digits of a percentage performance increase). Often the reason cited to change this value is performance. This recommendation is made for a few reasons: This will cause ESXi to change logical paths after every single I/O, instead of 1,000. Pure Storage recommends tuning this value down to the minimum of 1. Once it has issued 1,000 I/Os for that device, down that path, it will switch to a new logical path and so on. In other words, ESXi will choose a logical path, and start issuing all I/Os for that device down that path. By default, when Round Robin is enabled on a device, ESXi will switch to a new logical path every 1,000 I/Os. The I/O Operations Limit (sometimes called the “IOPS” value) dictates how often ESXi switches logical paths for a given device. The Round Robin Path Selection Policy allows for additional tuning of its path-switching behavior in the form of a setting called the I/O Operations Limit.
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