Dell S5000 Deployment/Configuration Manual page 34

Dell Networking S5000: Deployment of a Converged Infrastructure with FCoE
(MPIO). For Windows Server 2008 R2 Enterprise, three load balancing policy options are available. A
load balance policy is used to determine which path is used to process I/O.
PowerVault Load Balancing Policy Options:
1. Round-robin with subset — The round-robin with subset I/O load balance policy routes I/O
requests, in rotation, to each available data path to the RAID controller module that owns the
virtual disks. This policy treats all paths to the RAID controller module that owns the virtual disk
equally for I/O activity. Paths to the secondary RAID controller module are ignored until
ownership changes. The basic assumption for the round-robin policy is that the data paths are
equal. With mixed host support, the data paths may have different bandwidths or different data
transfer speeds.
2. Least queue depth with subset — The least queue depth with subset policy is also known as
the least I/Os or least requests policy. This policy routes the next I/O request to a data path
that has the least outstanding I/O requests queued. For this policy, an I/O request is simply a
command in the queue. The type of command or the number of blocks that are associated
with the command are not considered. The least queue depth with subset policy treats large
block requests and small block requests equally. The data path selected is one of the paths in
the path group of the RAID controller module that owns the virtual disk.
3. Least path weight with subset (Windows operating systems only) — The least queue depth with
subset policy is also known as the least I/Os or least requests policy. This policy routes the
next I/O request to a data path that has the least outstanding I/O requests queued. For this
policy, an I/O request is simply a command in the queue. The type of command or the
number of blocks that are associated with the command are not considered. The least queue
depth with subset policy treats large block requests and small block requests equally. The data
path selected is one of the paths in the path group of the RAID controller module that owns
the virtual disk.
34 Deployment of a Converged Infrastructure with FCoE
Deployment/Configuration Guide