Everything you want to know about the OM12 Cmdlets
Did you know there is a help topic about which cmdlets are new to Operations Manger 2012, which Operations Manager 2007 cmdlets have an equivalent Operations
Manager 2012 cmdlet ("renamed" cmdlets), and Operations Manager 2007 cmdlets that have no Operations Manager 2012 equivalent ("deprecated" cmdlets)?
Yes there is 
Just type Get-Help about_OpsMgr_Cmdlet_Names
Here it is:
TOPIC
about_OpsMgr_Cmdlet_Names
SHORT DESCRIPTION
Maps the System Center Operations Manager 2007 cmdlets to the
Operations Manager 2012 cmdlets.
LONG DESCRIPTION
All cmdlets in Operations Manager 2012 have new names, and can be
identified by the "SC" preceding the noun name. In some cases, the
verb associated with the cmdlet has also been updated.
This topic outlines which cmdlets are new to Operations Manger 2012,
which Operations Manager 2007 cmdlets have an equivalent Operations
Manager 2012 cmdlet ("renamed" cmdlets), and Operations Manager 2007
cmdlets that have no Operations Manager 2012 equivalent ("deprecated"
cmdlets).
------------------------------------------------------------------------
OPERATIONS MANAGER 2012 MODULE NAME
------------------------------------------------------------------------
Operations Manager 2007 snap-in
Microsoft.EnterpriseManagement.OperationsManager.Client
Operations Manager 2012 module
OM10
------------------------------------------------------------------------
NEW OPERATIONS MANAGER 2012 CMDLETS
------------------------------------------------------------------------
Enable-SCOMAgentProxy
Disable-SCOMAgentProxy
Enable-SCOMDiscovery
Disable-SCOMDiscovery
Set-SCOMManagementGroupConnection
Enable-SCOMMonitor
Disable-SCOMMonitor
Enable-SCOMMonitoringRule
Disable-SCOMMonitoringRule
Get-SCOMRunAsProfile
Update-SCOMRunAsProfile
------------------------------------------------------------------------
RENAMED CMDLETS
------------------------------------------------------------------------
Operations Manager 2007 Name Operations Manager 2012 Name
---------------------------- ----------------------------
Get-Agent Get-SCOMAgent
Install-Agent Install-SCOMAgent
Uninstall-Agent Uninstall-SCOMAgent
Approve-AgentPendingAction Approve-SCOMPendingManagement
Get-AgentPendingAction Get-SCOMPendingManagement
Reject-AgentPendingAction Deny-SCOMPendingManagement
Get-Alert Get-SCOMAlert
Resolve-Alert Set-SCOMAlert
Set-AlertDestination Set-SCOMAlert
Get-AlertHistory Get-SCOMAlertHistory
Get-Connector Get-SCOMConnector
Get-Diagnostic Get-SCOMDiagnostic
Remove-DisabledMonitoringObject Remove-SCOMDisabledClassInstance
Get-Discovery Get-SCOMDiscovery
Get-Event Get-SCOMEvent
Get-FailoverManagementServer Get-SCOMAgentManagementServerSetting
Get-GatewayManagementServer Get-SCOMGatewayManagementServer
Get-MaintenanceWindow Get-SCOMMaintenanceMode
New-MaintenanceWindow Start-SCOMMaintenanceMode
Set-MaintenanceWindow Update-SCOMMaintenanceMode
Get-ManagementGroupConnection Get-SCOMManagementGroupConnection
New-ManagementGroupConnection New-SCOMManagementGroupConnection
Remove-ManagementGroupConnection Remove-SCOMManagementGroupConnection
Export-ManagementPack Export-SCOMManagementPack
Get-ManagementPack Get-SCOMManagementPack
Install-ManagementPack Import-SCOMManagementPack
Uninstall-ManagementPack Remove-SCOMManagementPack
Get-ManagementServer Get-SCOMManagementServer
Set-ManagementServer Set-SCOMAgentManagementServerSetting
Set-ManagementServer Set-SCOMAgentManagementServerSetting
Get-Monitor Get-SCOMMonitor
Get-MonitorHierarchy Get-SCOMMonitor
Get-MonitoringClass Get-SCOMClass
Get-MonitoringObject Get-SCOMClassInstance
Get-MonitoringObjectGroup Get-SCOMGroup
Get-NotificationAction Get-SCOMNotificationAction
Get-NotificationEndpoint Get-SCOMNotificationEndpoint
Get-NotificationRecipient Get-SCOMNotificationRecipient
Disable-NotificationSubscription Disable-SCOMNotificationSubscription
Enable-NotificationSubscription Enable-SCOMNotificationSubscription
Get-NotificationSubscription Get-SCOMNotificationSubscription
Get-Override Get-SCOMOverride
Get-PrimaryManagementServer Get-SCOMAgentManagementServerSetting
Set-ProxyAgent Set-SCOMAgentlessManagedComputer
Get-Recovery Get-SCOMRecovery
Get-RelationshipClass Get-SCOMRelationship
Get-RelationshipObject Get-SCOMRelationshipInstance
Add-RemotelyManagedComputer Add-SCOMAgentlessManagedComputer
Get-RemotelyManagedComputer Get-SCOMAgentlessManagedComputer
Remove-RemotelyManagedComputer Remove-SCOMAgentlessManagedComputer
Get-ResultantCategoryOverride Get-SCOMOverride
Get-ResultantRuleOverride Get-SCOMOverride
Get-ResultantUnitMonitorOverride Get-SCOMOverride
Get-Rule Get-SCOMMonitoringRule
Get-RunAsAccount Get-SCOMRunAsAccount
Get-Task Get-SCOMTask
Start-Task Start-SCOMTask
Get-TaskResult Get-SCOMTaskResult
Get-UserRole Get-SCOMUserRole
Add-UserToUserRole Update-SCOMUserRole
------------------------------------------------------------------------
DEPRECATED OPERATIONS MANAGER 2007 CMDLETS
------------------------------------------------------------------------
Install-AgentByName
Get-AlertDestination
Remove-ConnectorFromTier
Add-ConnectorToTier
New-CustomMonitoringObject
Get-DefaultSetting
Set-DefaultSetting
New-DeviceDiscoveryConfiguration
Get-Diagnostic
Start-Discovery
New-LdapQueryDiscoveryCriteria
Get-MonitoringClassProperty
Get-MonitoringObjectPath
Get-MonitoringObjectProperty
New-MonitoringPropertyValuePair
Get-NotificationAction
Get-NotificationEndpoint
Get-NotificationRecipient
Disable-NotificationSubscription
Enable-NotificationSubscription
Get-NotificationSubscription
Get-OperationsManagerCommand
Get-PerformanceCounter
Get-PerformanceCounterValue
Get-Recovery
Add-RemotelyManagedDevice
Get-RemotelyManagedDevice
Remove-RemotelyManagedDevice
Get-RootManagementServer
Disable-Rule
Enable-Rule
Get-State
Get-Tier
New-Tier
Remove-Tier
New-WindowsDiscoveryConfiguration
SEE ALSO
about_OpsMgr_WhatsNew
Comments
Anonymous
January 01, 2003
very useful commands ------thanks Stefan.Anonymous
December 08, 2011
There is a typo in the documentation. There is no 'Update-SCOMMaintenanceMode' cmdlet. It should be 'SET-SCOMMaintenanceMode'.Anonymous
March 21, 2013
So what is the replacement to get-performancecounter? How do you get performance counters for a specific node?