Configuring VMware pathing via Powershell

August 19, 2009 Ed Goad

We have a fairly large VMware environment with a large number of LUNs. I did some performance reviews the other day and found that most of my FC traffic was passing through only 2 of the 4 ports in my Brocade switches.
This causes 2 problems: 1) I could potentially run into a bottleneck by being limited to IOPs and throughput, and 2) A large number of LUNs will have to fail-over if the primary path fails.

A quick bit of googling popped up the site: http://blogs.vmware.com/vipowershell/2008/07/managing-storag.html. This allows for all the LUNs on a single server to be changed to a Round-Robin policy (listed experimental, but still stable). Some tweaking and you could automatically set the preferred path for all LUNs on all servers.

A little more searching found the following script. This changes all LUNs on all servers to RR.


$Mypolicy = "rr"
Get-Datastore | where {$_.Type -eq "VMFS"} | %{(Get-View $_.ID).Info.Vmfs.Extent[0].DiskName} |%{
 $diskname = $_
 Get-VMHost | %{Get-View (Get-View $_.ID).configmanager.storageSystem} | %{
   $mpathpolicy = New-Object vmware.vim.HostMultipathInfoLogicalUnitPolicy
   $mpathpolicy.policy = $Mypolicy
   $_.SetMultipathLunPolicy($diskname,$mpathpolicy)
 }
}