Dell PowerVault MD3200i Deployment Manual

Also see for PowerVault MD3200i Series: Manual Update Rack Installation Instructions User guide Support Matrix

Contents

Dell PowerVault MD3200i Deployment Manual Manual pdf 77 page image

Appendix—Load Balancing 77CAppendix—Load BalancingLoad Balance PolicyMulti-path drivers select the I/O path to a virtual disk through a specific RAIDcontroller module. When the multi-path driver receives a new I/O to process,the driver tries to find a path to the current RAID controller module that ownsthe virtual disk. If the path to the current RAID controller module that ownsthe virtual disk cannot be found, the multi-path driver migrates the virtual diskownership to the secondary RAID controller module. When multiple paths tothe RAID controller module that owns the virtual disk exist, you can choose aload balance policy to determine which path is used to process I/O. Multipleoptions for setting the load balance policies let you optimize I/O performancewhen mixed host interfaces are configured.You can choose one of the following load balance policies to optimize I/Operformance:• Round robin with subset• Least queue depth with subset• Least path weight with subset (Windows operating systems only)Round Robin With SubsetThe round robin with subset I/O load balance policy routes I/O requests, inrotation, to each available data path to the RAID controller module that ownsthe virtual disks. This policy treats all paths to the RAID controller module thatowns the virtual disk equally for I/O activity. Paths to the secondary RAIDcontroller module are ignored until ownership changes. The basic assumptionfor the round-robin policy is that the data paths are equal. With mixed hostsupport, the data paths might have different bandwidths or different datatransfer speeds.