Setting up Persistent Scratch Space for an Arbitrary Number of ESXi Hosts

We've been configuring a large number of ESXi servers that don't have local hard drives.  As such, we need to set up each system's scratch location on persistent storage, as per that KB article from VMware.

That KB Article has a great section devoted to performing the process from PowerCLI and it basically takes you through the whole thing, soup to nuts, for a single ESXi host.  That's all well and good, but what if you've got 16 hosts?  Or 32?  Or 64?  Well, with a few minor changes to the procedure that they've outlined, you can very easily target every ESXi host in an environment.  Bear in mind that this process does require a host reboot, so make sure that you have your ducks in a row (and preferably do this before you place any VMs onto the cluster).

Instead of their step 6, I used this command to create a folder for all ESX hosts in the inventory:
get-vmhost | foreach {new-item ".$($_.name)/scratch" -itemtype directory}

Instead of their step 8, I used this command to change the setting on all ESX hosts in the inventory:
get-vmhost | Set-VMHostAdvancedConfiguration -name "ScratchConfig.ConfiguredScratchLocation" -Value "/vmfs/volumes/LUN-ID/.$($_.name)/scratch"

Make sure to change the path in there to whatever LUN you want to work with, as "LUN-ID" isn't likely to work in your environment.

If you're feeling masochistic (or just want to strip the domain suffix from the hostname), you can replace all of the
".$($_.name)/scratch" instances with ".$($_.name.split(".")[0])/scratch"

If you want to filter either command to hit only a subset of the hosts, you can change the "get-vmhost" command to something more specific like "get-vmhost esx01".

So, here's the assembled process in its entirety:

1) Launch PowerCLI
2) Connect to vCenter:
connect-viserver <vCenter name>
3) Get the list of datastores in the environment:
get-datastore
4) Mount the datastore through your PowerCLI session:
New-PSDrive -Name "DS" -Root \ -PSProvider VimDatastore -Datastore (Get-Datastore "<Datastore Name>")
5) Move into the mounted datastore:
cd DS:
6) Create a folder for each ESXi Host:
get-vmhost | foreach {new-item ".$($_.name)/scratch" -itemtype directory}
7) If desired, check the current scratch location (I'm mostly including this to keep my numbers in line with the original article's numbers):
get-vmhost | Get-VMHostAdvancedConfiguration -Name "ScratchConfig.ConfiguredScratchLocation"
8) Set the Scratch location for the hosts:
get-vmhost | Set-VMHostAdvancedConfiguration -name "ScratchConfig.ConfiguredScratchLocation" -Value "/vmfs/volumes/LUN-ID/.$($_.name)/scratch"
9) Reboot the ESXi hosts.

Update: Since set-vmhostadvancedconfiguration is deprecated (although still works, at least for now), here's the new way to do step 8 (although I haven't actually done it this way yet):
get-vmhost | get-advancedsetting -name "ScratchConfig.ConfiguredScratchLocation" | set-advancedsetting -value "/vmfs/volumes/LUN-ID/.$($_.entity)/scratch"

Update 2: I've been doing this a lot and have optimized the process a bit.  Here it is in 5 steps (after connecting the PowerCLI session to the vCenter server).  Bear in mind that each of these is its own, single line... some of them have a lot of string manipulation in it to build the correct path for the scratch config.

1) Get the target Datastore
$thisDataStore = Get-datastore LogDataStore
2) Mount the Datastore via PowerShell
New-PSDrive -Name "DS" -Root \ -PSProvider VimDatastore -Datastore $thisDataStore
3) Create the per-host scratch space folders on the datastore
get-vmhost | foreach {new-item "DS:\.$($_.name.split('.')[0])/scratch" -itemtype directory}
4) Reconfigure the ESXi hosts to use those folders.
get-vmhost | foreach {$_ | get-advancedsetting -name "ScratchConfig.ConfiguredScratchLocation" | set-advancedsetting -Value "$($thisDataStore.ExtensionData.info.url.replace('ds://','')).$($_.name.split('.')[0])/scratch" -confirm:$false}

5) Reboot the ESXi hosts.