Infrastructure Adventures

I have been experimenting with SSD and Host Cache in my home lab. I am also trying to do as much with PowerCLI as possible. Coming from a Unix background I think it would be awesome to be able to do basically everything in vSphere (and vCloud) via a CLI. Turns out there are not any cmdlets to enable the SSD options on LUNs or manage Host Cache configurations, so I wrote some functions to do that.

I imagine this could be particularly useful for someone who plans on using Host Cache and has a clusters of hosts they need to configure to use that feature. My plan is to write more “missing” cmdlets and make a module available in the near future.

Set-SSDScsiLUN and Get-SSDScsiLUN

Host Cache requires data store backed by SCSI LUNs to be marked as SSDs. Presumably ESXi will detect and automatically mark actual SSD backed data stores as SSD. But for home labs or instances where ESXi doesn’t correct identify the SCSI LUN as an SSD, the LUN can be marked as SSD manually. This can be done via ESXCLI and it turns out you can call ESXCLI via PowerCLI’s Get-ESXCLI cmdlet.

The Set-SSDScsiLUN function is a PowerCLI wrapper for the Get-ESXCLI cmdlet that will mark the specified SCSI LUNs as SSD backed. This works with the pipeline so you can mark a LUN with a specific Canonical Name as SSD for an entire cluster or data center with a single line.

Since this is a wrapper for ESXCLI and involves calling a process to “re-claim” all the LUNs there is a slight lag between running this command and having the LUNs shows up as SSD.

Function Set-SSDScsiLUN {
	<#
		.SYNOPSIS
			Adds or Removes the "enable_ssd" option for a specified SCSI LUN.

		.DESCRIPTION
			The Set-SSDScsiLUN function uses the ESXCLI to update the SATP claim rule for the specified SCSI LUN. Please note there is a few second delay for the claim rules to run and for the data store to show up as SSD.
			
		.PARAMETER  ScsiLun
			Use this parameter to specify the SCSI LUN you wish to enable/disable the SSD option.

		.PARAMETER  Disabled
			Used to disable/unset the SSD option on the sprcified LUN.
		
		.PARAMETER  ReClaimOnly
			It's possible to end up in a situation where the claim rule has been added or removed, but for whatever reason the claim process does not complete successfully. This can be caused by running this function several rimes in a row. Using this switch will just rerun the claim process. If you run the Set-SSDScsiLUN function and the change does not take effect, you may want to try running with the ReClaimOnly switch.	
		
		.EXAMPLE
			C:\PS> Set-SSDScsiLUN -ScsiLun $SCSILUN
			
			Enables the SSD option for $SCSILUN
			
		.EXAMPLE
			C:\PS> Set-SSDScsiLUN -ScsiLun $SCSILUN -Disabled
			
			Disables the SSD option for $SCSILUN
		
		.Example
			C:\PS> Get-VMHost | Get-ScsiLun -CanonicalName $SCSILUN | Set-SSDScsiLUN
			
			Enables the SSH option for all hosts with a SCSI LUN matching the Canonical Name of $SCSILUN (e.g. mpx.vmhba1:C0:T1:L0)

		.EXAMPLE
			C:\PS> Get-Datastore | where { $_.name -like "*HostCache*" } | Get-ScsiLun | Set-SSDScsiLUN
			
			Enables the SSD option for all LUNs that belong to data stores with "HostCache" as part of thier name.			
	
		.NOTES
			Function has only been tested with vSphere 5.1, should work with vSphere 5.0. This fucntion has only been tested for local disks.		
	
		.LINK

http://infrastructureadventures.com/

	#>
	
	[CmdletBinding()]
	Param (
		[Parameter(Mandatory=$True,ValueFromPipeline=$True)]
		$ScsiLun,
		[Switch]
		$Disabled,
		[Switch]
		$ReClaimOnly
	)

	BEGIN {}

	PROCESS {

		if ( ($ScsiLun.GetType()).name -eq "String" ) {
			$ScsiLun = Get-ScsiLun -CanonicalName $ScsiLun
		}

		$LUN_CName = $ScsiLun.CanonicalName

		$VMHost = get-vmhost -name $ScsiLun.VMHost
		$ESXCLI = $VMHost | get-EsxCli
		$SATP = ($ESXCLI.storage.nmp.device.list($LUN_CName))[0].StorageArrayType
		$ClaimRules = $ESXCLI.storage.nmp.satp.rule.list()

		if ( $ReClaimOnly -eq $False ) {
			if ( $Disabled -eq $True ) {
				if ( $ESXCLI.storage.core.device.list($LUN_CName)[0].IsSSD -eq "true" ) {
					foreach ( $Rule in $ClaimRules ) {
						if ( $Rule.Device -eq $LUN_CName -and $Rule.Options -eq "enable_ssd" ) {
						$ESXCLI.storage.nmp.satp.rule.remove($FALSE,"","",$LUN_CName,"","","enable_ssd","","",$SATP,"","","") | Out-Null
						$ESXCLI.storage.core.claiming.reclaim($LUN_CName)
						}
					}
				}
			} elseif ( $Disabled -eq $False ) {
				if ( $ESXCLI.storage.core.device.list($LUN_CName)[0].IsSSD -eq "false" ) {
					foreach ( $Rule in $ClaimRules ) {
						if ( $Rule.Device -eq $LUN_CName -and $Rule.Options -eq "enable_ssd" ) {
							$RuleExists = $True
							break
						}
					}
					if ( $RuleExists ) {
						$ESXCLI.storage.core.claiming.reclaim($LUN_CName)
					} else {
						$ESXCLI.storage.nmp.satp.rule.add($FALSE,"","",$LUN_CName,"",$FALSE,"","enable_ssd","","",$SATP,"","","") | Out-Null
						$ESXCLI.storage.core.claiming.reclaim($LUN_CName)
					}
				}
			}
		} elseif ( $ReClaimOnly ) {
			$ESXCLI.storage.core.claiming.reclaim($LUN_CName)
		}
	$ScsiLun
	}

	END {}
}

This next function will output the LUNs in an existing data store that have been marked as SSD. I went back and forth on what should be the input and output for this function, and I admit I”m still not entirely satisfied. If anyone has any suggestions, i’d be up for a re-write.

Function Get-SSDScsiLUN {
	<#
		.SYNOPSIS
			Gets SCSI LUN objects that are marked as SSD.

		.DESCRIPTION
			The Get-SSDScsiLUN function outputs the SCSI LUNs that belong to a data store that are marked as SSD based. Please note that it takes a couple of seconds for the changes made by the Set-SSDScsiLUN function to complete.

		.PARAMETER  DataStore
			Use this parameter to specify the data store you wish to see if the SSD option has been set.

		.EXAMPLE
			C:\PS> Get-SSDScsiLUN -DataStore $DataStore
			
			Outputs to the SCSI LUN objects that are marked as SSD for the specified $DataStore.
			
		.NOTES	
			Function has only been tested with vSphere 5.1, should work with vSphere 5.0.	
	
		.LINK

http://infrastructureadventures.com/

	#>
	
	[CmdletBinding()]
	Param (
		[Parameter(ValueFromPipeline=$True)]
		$DataStore
	)

	BEGIN {}

	PROCESS {
		if ( $DataStore ) {
			if ( ($DataStore.GetType()).name -eq "String" ) {
				$DataStore = Get-Datastore -Name $DataStore
			}
		} else {
			$DataStore = Get-DataStore | where { $_.Type -eq "VMFS" }
		}
		$DataStore | where { $_.Type -eq "VMFS" } | Get-ScsiLUN | where { $_.ExtensionData.Ssd -eq "True" }
	}

	END {}
}

Set-VMHostCache and Get-VMHostCache

Now really this is all about setting the Host Cache Space on an SSD backed LUN and the Set-VMHostCache can be used to do just that. Simply provide it a SSD backed data store object and it will configure a Host Cache Space as large as the available free space on the data store, or optionally provide a size in GBs. Specifying zero (0) for the size will turn Host Cache off.

And there is a Get-VMHostCache function which can be used to see the Host Cache Space defined on each data store.

Function Set-VMHostCache {
	<#
		.SYNOPSIS
			Configures Host Cache Space on a specified SSD backed Data Store.

		.DESCRIPTION
			The Set-VMHostCache function configures Host Cache Space on a specified SSD backed Data Store.
			
		.PARAMETER  DataStore
			Use this parameter to specify the Data Store you would like to use for the Host Cache Space.
		
		.PARAMETER  Space
			This parameter specifies the space in GBs that should be used for the Host Cache Space. Omitting this parameter will cause the Host Cache Space to be set to the maximum amount of space available on the data store.

		.PARAMETER  Disabled
			Used to disable/remove the Host Cache Space from the specified Data Store.
		
		.EXAMPLE
			C:\PS> Set-VMHostCache -DataStore $datastore -Size 15
			
			Sets the Host Cache Space on Data Store $datestore to 15 GBs.
			
		.EXAMPLE
			C:\PS> Set-VMHostCache -DataStore $datastore -Disabled
			
			Removes the Host Cache Space from $datastore.

		.EXAMPLE
			C:\PS> Get-VMHost | New-Datastore -VMFS -Path $SSDSCSILUN -Name "HostCache" | Set-VMHostCache
			
			Creates a Data Store on each host with the SCSI LUN $SSDSCSILUN called HostCache and then sets the Host Cache Space to equal the maximum space available on the data store.		
	
		.NOTES
			Function has only been tested with vSphere 5.1, should work with vSphere 5.0.		
	
		.LINK

http://infrastructureadventures.com/

	#>
	
	[CmdletBinding()]
	Param (
		[Parameter(Mandatory=$True,ValueFromPipeline=$True)]
		$DataStore,
		[int]
		$Space,
		[Switch]
		$Disabled
	)

	BEGIN {}

	PROCESS {

		if ( ($DataStore.GetType()).name -eq "String" ) {
			$DataStore = Get-Datastore -Name $DataStore
		}

		$HostCacheConfigurationSpec = New-Object VMware.Vim.HostCacheConfigurationSpec
		$HostCacheConfigurationSpec.datastore = New-Object VMware.Vim.ManagedObjectReference
		$HostCacheConfigurationSpec.datastore.type = "Datastore"
		$HostCacheConfigurationSpec.datastore.Value = ($DataStore.id).substring(10,13)

		if ( $Disabled ) {
			$HostCacheConfigurationSpec.swapSize = 0
		} else {
			if ( $Space ) {
				$SpaceMB = $Space * 1024
				if ( $SpaceMB -gt $DataStore.FreeSpaceMB ) {
					Write-Warning ("Specified Host Cache Space size is larger then avialable space, setting Host Cache Space size to maximum avialable space.")
					$HostCacheConfigurationSpec.swapSize = $DataStore.FreeSpaceMB
				} else {
					$HostCacheConfigurationSpec.swapSize = $SpaceMB
				}
			} else {
				$HostCacheConfigurationSpec.swapSize = $DataStore.FreeSpaceMB
			}
		}

		$HostCacheConfigurationManager_ID = ("HostCacheConfigurationManager-cacheConfigManager-" + (($DataStore.ExtensionData.host[0].Key.value).split("-"))[1])
		$HostCacheConfigurationManager = Get-View -Id $HostCacheConfigurationManager_ID
		$HostCacheConfigurationManager.ConfigureHostCache_Task($HostCacheConfigurationSpec) | Out-Null

		$DataStore

	}

	END {}
}

Function Get-VMHostCache {
	<#
		.SYNOPSIS
			Gets the Host Cache configuration for the specified host.

		.DESCRIPTION
			The Get-VMHostCache function gets the Host Cache configuration for a specified host. It displays the amount of space on each data store that has been configured as Host Cache Space.
			
		.PARAMETER  VMHost
			Use this parameter to specify the Host that you wish to get the host cache configuration.
		
		.EXAMPLE
			C:\PS> Get-VMHostCache -VMHost $Host
			
			Gets the Host Cahce configuration for $Host
			
		.NOTES
			Function has only been tested with vSphere 5.1, should work with vSphere 5.0.		
	
		.LINK

http://infrastructureadventures.com/

	#>
	
	[CmdletBinding()]
	Param (
		[Parameter(Mandatory=$True,ValueFromPipeline=$True)]
		$VMHost
	)

	BEGIN {}

	PROCESS {

		if ( ($VMHost.GetType()).name -eq "String" ) {
			$VMHost = Get-VMHost -Name $VMHost
		}

		$HostCacheConfigurationManager_ID = ("HostCacheConfigurationManager-cacheConfigManager-" + (($VMHost.id).split("-"))[2])
		$HostCacheConfigurationManager = Get-View -Id $HostCacheConfigurationManager_ID

		foreach ( $HostCacheDataStore in $HostCacheConfigurationManager.CacheConfigurationInfo ) {
			$DataStore_ID = ("Datastore-" + $HostCacheDataStore.key.value)
			$Datastore = Get-DataStore -Id $DataStore_ID

			$DataStore | select name, @{Name="HostCacheSpaceGB";Expression={$HostCacheDataStore.SwapSize / 1024}}, FreeSpaceGB, CapacityGB
		}
	}

	END {}
}