While doing some iSCSI LUN testing for a certain storage vendor, I was looking for a way to add multiple hard disks to a single VM across each iSCSI LUN whose name matched a certain pattern. In my case, all luns I was testing against had the full lun path in their name so the were similar to lun1.naa.600144f0dcb8480000005142553e0001 (thanks to Alan Renouf’s post “PowerCLI: Mass provision datastore’s” for guidance on  scripting datastore creation).

However, I do not have all luns mapped to every vSphere host. Easy enough to get around this in PowerCLI. The following script prompts for the Virtual Machine name, size and hard disk format. Then filters the datastores by that VM’s vSphere host and our common string in the datastore name.

$vmname = read-host "VM Name to add disks to"

$vm = get-vm $vmname

$size = read-host "Disk Size (GB)"

$format = read-host "Disk Format (thin, thick, EagerZeroedThick)"

$datastores = $vm | Get-VMHost | Get-Datastore | Where-Object {$_.name -like "lun*naa*"}

foreach ($item in $datastores){
$datastore = $item.name
write-host "Adding new $size VMDK to $vm on datastore $datastore"
New-HardDisk -vm $vm -CapacityGB $size -Datastore $datastore -StorageFormat $format
}

There are a lot of parameters for the New-HardDisk cmdlet that I don’t specify because the defaults were what I already wanted (e.g. Persistence, Controller, DiskType, etc.). Some, like StorageFormat which defaults to Thick Lazy Zeroed, I wanted to control.

In another case, I wanted to add multiple disks from one datastore to a vm.

### Get VM/Disk Count/Datastore information ###
$vmname = read-host "VM Name to add disks to"
$num_disks = read-host "number of disks to add"
$ds = read-host "Datastore to place the VMDK"
$format = read-host "Disk Format (thin, thick, EagerZeroedThick)"
$size = read-host "Disk Size (GB)"

$vm = get-vm $vmname
$datastore = get-datastore -name $ds
$x=0

### Add $num_disks to VM
while ($x -lt $num_disks){
write-host "Adding $size VMDK to $vm on datastore $datastore"
New-HardDisk -vm $vm -CapacityGB $size -Datastore $datastore -StorageFormat $format
$x++
}

You can read more about the New-HardDisk cmlet at:
http://www.vmware.com/support/developer/PowerCLI/PowerCLI51/html/New-HardDisk.html