Manually load balancing / setting LUN paths.

[dawoo]

I'm wanting to manually load balance my LUNs, there are 4 paths and I'd like to cycle each LUN through the next path and loop back round. Am using vSphere 4 Update 1.

Looking through the web I've found these two articles provide the code I'm after but both error for me.

http://vmjunkie.wordpress.com/2009/01/29/balancing-lun-paths-on-your-esx-hosts-with-powershell/

http://doitsmarter.blogspot.com/

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---

1. Get information from user

$vc = Read-Host "Please enter the vCenter Server name:"

$uname = Read-Host "Please enter the username to connect to the vCenter server:"

$upass = Read-Host "Please enter the associated password:"

$clusterName = Read-Host "Please enter the Cluster name:"

Write-Host "Connecting to vCenter server $vc, please wait." -BackgroundColor Black -ForegroundColor White

Connect-VIserver $vc -user $uname -password $upass | Out-Null

###

1. Retrieve ESX hosts in Cluster

$VMHosts = Get-Cluster $clusterName | Get-VMHost

1. Run through this loop for each host in the cluster

foreach ($VMHost in $VMHosts)

{

$luns = @($VMHost|get-scsilun -luntype disk| where-object {$_.ConsoleDeviceName -like "/vmfs/devices/disks/vml*"} | Sort-Object CanonicalName)

$firstLUNPaths = Get-ScsiLunPath $luns[0]

$numPaths = $firstLUNPaths.Length

$count = 0

foreach ($lun in $luns)

{

if ($count -ge $numPaths)

{

$count = 0

}

$paths = Get-ScsiLunPath -ScsiLun $lun

$lun|Set-ScsiLun -MultipathPolicy Fixed -PreferredPath $paths[$count]

$count += 1

1. Sleep for 30 seconds to prevent array saturation.

Start-Sleep -Seconds 30

}

}

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Initially I found the script stumbled on the $luns[0] implying the value is null or empty. I Replaced vml with naa. Now I receive "One or more missing mandetory parameters SCSI LUN". I assumed an error with the syntax but am not able to establish quite what.

Now, if I run some of the commands at the command line I find I get out usable output. But by piping the same line into an array or variable then Write-Host of the content I see "VMware.VIMAutomation.ViCore.Impl.V1" (and so on).

Judging by the dates of the blog posts I'm of the opinion the latest PowerCLI (v4 build 264274) may be returning the information in a different manner, I am correct with my assumption?

Can you guess what my next question will be? How would I do this now?

Any assistance is appreciated and rewarded (in points not beer).

Thanks,

Darren.

[LucD · Accepted solution]

The "vml", "naa"... depends on the type of storage your LUNs are located on.

The problem with the next statement is that you need to specify the -Scsilun parameter.

This can be a positional parameter (without -Scsilun) but then it has to come in position 2.

See the Get-ScsiLunPath page.

Try the attached script.

I changed that line and it works for me.

____________

Blog: LucD notes

Twitter: lucd22

[dawoo]

Many thanks (again) LucD.

Amended script works like a a treat, not that I doubted it by the way.

Cheers,

Darren.

(@dawoo)