DefinIT

Path Selection Policies after removing PernixData

pernixdataRecently I have had the pleasure to use PernixData but I did come across a bit of a ‘gotcha’ after uninstalling it from my hosts.

If like me you use iSCSI then you will likely spend a bit of time setting up your Path Selection Polices to suit your specific needs, so it was interesting to note the following.

When you do uninstall and remove PernixData from your hosts your Path Selection Polices do not revert back to your original configuration rather they revert back to the default vSphere setting of MRU (Most recently used).

This is worth noting as this is not mentioned in the documentation PernixData provide.

UPDATE – After being contacted by the guys at PernixData I can confirm they will be updating their documentation shortly to reflect this outcome.

VMware PowerCLI – Set Path Selection Policy on all LUNs for a host

Just a quick script to set the Path Selection Policy on any LUNs on a host that do not have your target policy enabled. The script sets the server to Maintenance mode first, evacuating any VMs if you are in a full DRS automated environment. While this is not strictly necessary, it was required for my production environment just to be safe.

param( [string] $vCenterServer = $(Read-Host -prompt "Enter vCenter Server Name"),
[string] $TargetPolicy = $(Read-Host -Prompt "Enter target policy (RoundRobin, Fixed or MostRecentlyUsed)"),
[string] $TargetHost = $(Read-Host -Prompt "Enter target Host"),
[switch] $WhatIf)

# 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"}

Connect-VIServer $vCenterServer | out-null

Write-Host "Connected to: " $vCenterServer -ForegroundColor Green
Write-Host "Target PSP: " $TargetPolicy -ForegroundColor Yellow
Write-Host

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

Write-Host "Setting Policy to"$TargetPolicy" on "$TargetHost -ForegroundColor Green

if($WhatIf) {
$vHost = Get-VMHost -Name $TargetHost
$vHost | Set-VMHost -State Maintenance -Evacuate -WhatIf
$vHost | Get-ScsiLun -LunType "disk" -ErrorAction SilentlyContinue | where {$_.IsLocal -eq $false -and $_.MultipathPolicy -ne $TargetPolicy} | Set-ScsiLun -MultipathPolicy $TargetPolicy -WhatIf
$vHost | Set-VMHost -State Connected -WhatIf
} else {
$vHost = Get-VMHost -Name $TargetHost
Write-Host "Setting "$TargetHost" to Maintenance Mode" -ForegroundColor White
$vHost | Set-VMHost -State Maintenance -Evacuate
$vHost | Get-ScsiLun -LunType "disk" -ErrorAction SilentlyContinue | where {$_.IsLocal -eq $false -and $_.MultipathPolicy -ne $TargetPolicy} | Set-ScsiLun -MultipathPolicy $TargetPolicy
Write-Host "Exiting Maintenance mode on"$TargetHost -ForegroundColor White
$vHost | Set-VMHost -State Connected
}