Dell Storage with Microsoft Storage Spaces Deployment Guide

Configuring Multipath I/O (MPIO) on each server enables Windows server to use alternate paths to hard drive in the event of a failure and provides load balancing. When properly cabled and when using dual-port SAS physical disks, each server has two physical paths to each physical disk.

Complete the following task before disks are added to a pool.

1. To enable MPIO automatic claim for SAS drives, run the following command:

   Enable-MSDSMAutomaticClaim -BusType SAS

2. To set the global default policy to LB, run the following command:

   Set-MSDSMGlobalDefaultLoadBalancePolicy -Policy LB

   This sets the global value to LB. Any new drive added to the solution will be automatically configured as LB. Dell recommends using Least Blocks (LB) for SSDs and LB for hard drives for optimal performance in most applications.

To configure a different load balance policy for different groups of drives please run the following code. Use the drive model identifier in order to make quick changes. If you have a combination of HDDs and SSDs then you have to configure manually.

1. To know the Target H/W Identifier value, run the following command:

   mpclaim -e

2. To set MPIO policy for the specified H/W Identifier (you MUST include all trailing spaces), run the following command:

   mpclaim -l -t "Target H/W Identifier" Policy Number

   Policy Number options:

   0 = Clear the policy 1 = Fail-Over policy 2 = Round Robin 6 = Least Blocks

   You must run this command for every different drive model type. There are other load-balancing policies available but these are the only ones Dell supports.

3. To display the current target-wide MPIO policies, run the following command:

   mpclaim -s -t