Fix Path Selection Policy for a whole vCenter Cluster

These last few weeks, I’ve been toying with PowerCLI (and PowerShell for that matter). One thing I do have to say, is that Microsoft finally did it right! It’s a useable, program-able command line interface for Windows after all! Thanks to Ivo Beerens and his post “Best practices for HP EVA, vSphere 4 and Round Robin multi-pathing“, I was able to come up with the below:

# LICENSE:     GNU General Public License v2. (see LICENSE.txt)
# COPYRIGHT:   Copyright 2010 Christian Heim &lt;christian.heim@barfoo.org&gt;

# Add the VI-Snapin if it isn&#039;t loaded already
if ( (Get-PSSnapin -Name &quot;VMware.VimAutomation.Core&quot; -ErrorAction SilentlyContinue) -eq $null )
{
    Add-PSSnapin -Name &quot;VMware.VimAutomation.Core&quot;
}

if ($args.length -lt 2) {
    Write-Host
    Write-Host &quot;fix_multipathing:  &quot;
    Write-Host &quot;     - Display-Name of the vCenter cluster, we should check all LUNs&quot;
    Write-Host &quot;                     on all available Hosts, and set the Path Selection Policy&quot;
    Write-Host &quot;                     to the selected one.&quot;
    Write-Host &quot;&quot;
    Write-Host &quot;              - Path Selection Policy&quot;
    Write-Host &quot;                     Possible:&quot;
    Write-Host &quot;                        - RoundRobin (VMW_PSP_RR, Round Robin)&quot;
    Write-Host &quot;                        - Fixed (VMW_PSP_FIXED, Fixed)&quot;
    Write-Host &quot;                        - MostRecentlyUsed (VMW_PSP_MRU , Most Recently Used)&quot;
    Write-Host
    exit 1
} 

$vcserver = &quot;vcenter.home.barfoo.org&quot;
$cluster  = $args[0]
$target_policy = $args[1]

# Since I do have only SVC-Disks connected to my hosts, I limit the search to those
$canonical_name = &quot;naa.6005076801808021*&quot;

Write-Host &quot;Target vCenter Cluster: &quot; $cluster
Write-Host &quot;Target PSP: &quot; $target_policy
Write-Host

switch ($target_policy) {
        RoundRobin { $display_policy = &quot;VMW_PSP_RR&quot;; }
        MostRecentlyUsed { $display_policy = &quot;VMW_PSP_MRU&quot;; }
        Fixed { $display_policy = &quot;VMW_PSP_FIXED&quot;; }
        default { Write-Warning &quot;Unknown PSP selected! Please consult the help and try again.&quot;; exit }
}

Connect-VIServer $vcserver &gt;/dev/null 2&gt;&amp;1

Write-Host &quot;Found &quot;@(Get-VMHost -location ( get-cluster $cluster ) | Get-ScsiLun -CanonicalName $canonical_name -LunType &quot;disk&quot; | where {$_.MultipathPolicy -ne $target_policy }).Count&quot; LUNs in &quot;$cluster&quot; not using Path Selection Policy &quot;$display_policy
Get-VMHost -location ( get-cluster $cluster ) | Get-ScsiLun -CanonicalName $canonical_name -LunType &quot;disk&quot; |  where {$_.MultipathPolicy -ne $target_policy } | Set-ScsiLun -MultipathPolicy $target_policy  &gt;/dev/null 2&gt;&amp;1

# LICENSE: GNU General Public License v2. (see LICENSE.txt)

# Add the VI-Snapin if it isn't loaded already

if ( (Get-PSSnapin -Name "VMware.VimAutomation.Core" -ErrorAction SilentlyContinue) -eq $null )

{

Add-PSSnapin -Name "VMware.VimAutomation.Core"

}

if ($args.length -lt 2) {

Write-Host

Write-Host "fix_multipathing: "

Write-Host " - Display-Name of the vCenter cluster, we should check all LUNs"

Write-Host " on all available Hosts, and set the Path Selection Policy"

Write-Host " to the selected one."

Write-Host ""

Write-Host " - Path Selection Policy"

Write-Host " Possible:"

Write-Host " - RoundRobin (VMW_PSP_RR, Round Robin)"

Write-Host " - Fixed (VMW_PSP_FIXED, Fixed)"

Write-Host " - MostRecentlyUsed (VMW_PSP_MRU , Most Recently Used)"

Write-Host

exit 1

}

$vcserver = "vcenter.home.barfoo.org"

$cluster = $args[0]

$target_policy = $args[1]

# Since I do have only SVC-Disks connected to my hosts, I limit the search to those

$canonical_name = "naa.6005076801808021*"

Write-Host "Target vCenter Cluster: " $cluster

Write-Host "Target PSP: " $target_policy

Write-Host

switch ($target_policy) {

RoundRobin { $display_policy = "VMW_PSP_RR"; }

MostRecentlyUsed { $display_policy = "VMW_PSP_MRU"; }

Fixed { $display_policy = "VMW_PSP_FIXED"; }

default { Write-Warning "Unknown PSP selected! Please consult the help and try again."; exit }

}

Connect-VIServer $vcserver >/dev/null 2>&1

Write-Host "Found "@(Get-VMHost -location ( get-cluster $cluster ) | Get-ScsiLun -CanonicalName $canonical_name -LunType "disk" | where {$_.MultipathPolicy -ne $target_policy }).Count" LUNs in "$cluster" not using Path Selection Policy "$display_policy

Get-VMHost -location ( get-cluster $cluster ) | Get-ScsiLun -CanonicalName $canonical_name -LunType "disk" | where {$_.MultipathPolicy -ne $target_policy } | Set-ScsiLun -MultipathPolicy $target_policy >/dev/null 2>&1

This works great, however you could make it work on the whole vCenter inventory, which I don’t want. We usually add LUNs to a single cluster at one time. Only thing you might need to change, is the canonical name. Mine simply says “find all SVC LUNs” and you might need to change it, if you’re using a different storage.

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