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Rolling Back a Failed Migration

If iSCSI initiators have successfully reconnected to the new iSCSI Software Target server, the migration is successful and complete. This topic discusses the tasks that should be performed in the event of a failed migration .

Restoring the role if the migration failed

If migration does not complete successfully, a rollback procedure is required to undo any changes to the source server, other servers, and client computers, and then restore the source server back into service.

Rollback requirements

The rollback procedure requires that the source server is available in the same state as it was after the “Remove the network identity of the iSCSI Software Target server” step in the “Prepare your source server” section. For more information, see Remove the network identity of the iSCSI Software Target server.

During the source server preparation steps, none of the steps performed permanently changed the existing configuration of the server because all of the operations were substantially read operations.

The estimated time to complete the rollback is equivalent to the time that it takes to re-establish the network identity of the source server. This operation may require rolling back changes to the DHCP servers, DNS server, or Active Directory Domain controllers.

Roll back changes on other computers in the enterprise

The other computers in the enterprise that are affected by migrating Microsoft iSCSI Software Target are the iSCSI initiators that were using the iSCSI Software Target server.

In the case of a rollback, the iSCSI initiators that were configured to log on to the destination server need to be rolled back to the source server. Use the following Windows PowerShell commands:

  1. To log out of an existing iSCSI session:

    PS > & iscsicli.exe sessionlist
    PS > & iscsicli.exe LogoutTarget <session id>
    
    
  2. To discover the iSCSI Software Target source server:

    PS > & iscsicli AddTargetPortal <source-server-ip-address> 3260
    PS > iscsicli.exe ListTargets
    
    
  3. To log on to the targets on the iSCSI Software Target source server:

    PS > & iscsicli.exe  LoginTarget <target IQN> T < source-server-ip-address> 3260 Root\ISCSIPRT\0000_0 * * * * * * * * * * * * *
    
    

Roll back the source server in a standalone configuration

This step will undo the network identity removal that is described in the “Remove the network identity of the iSCSI Software Target server’ section.

Possible scenarios include:

  • Restore the NetBIOS fully qualified domain name to the source server, and assign the required IP addresses to the source server.

  • Restore any DNS assignments (for example, reverse lookup and DHCP assignment).

  • Restore any identities that were previously assigned in Active Directory.

Each scenario requires potentially updating information in the DNS server, Active Directory, or DHCP server, according to the methodology that is used to assign IP addresses and network names to the servers in the enterprise.

The intent of this step is to ensure that upon completion of the migration steps, the iSCSI initiators are able to locate the source server (either through explicit reconfiguration, or implicitly through the computer name or IP address re-assignment).

For more information, see the IP Configuraiton Migration Guide (http://go.microsoft.com/fwlink/?LinkID=128513).

Roll back the source server in a failover cluster

Roll back cluster network name changes

This step will undo the network identity removal described in the “Remove the network identity of the iSCSI Software Target server” section.

In a clustered configuration, network names are established by the Server Principal Name that is assigned in Active Directory to the cluster when the cluster was formed.

To re-establish network names that were possibly deleted or retired, the cluster administration utilities must be used. For more information, see Migrating Settings to a Failover Cluster Running Windows Server 2008 R2.

Move resource groups to the preferred owner node

After the client access points have been re-established, the resource groups need to be moved back to their preferred owner node.

The resource groups were moved to a single node as part of the steps that you performed in the “Capture the existing settings: clustered configuration” section.

To move the resource groups back to their preferred owner node, use the following Windows PowerShell command:

PS > & cluster.exe /cluster:<cluster name> GROUP <group name> /moveto:<node name>

noteNote
The group names and the node names were captured during the preparation steps.

Roll back Microsoft iSCSI Software Target 3.3 on the destination server in a standalone configuration

The steps that are required to roll back a destination server that is running Windows Server 2008 R2 consist of uninstalling the product. This can be accomplished by using the following Windows PowerShell commands:

  1. To find the package GUID:

    PS > Get-WmiObject -Class Win32_product | Where-Object { $_.packageName –match 'iscsitarget'}
    
    
  2. To uninstall the package:

    PS > & msiexec.exe /uninstall <Identifying Number > /qr
    
    

Roll back Microsoft iSCSI Software Target 3.3 on the destination server in a failover cluster

The steps that are required to roll back a destination server that is running Windows Server 2008 R2 consist of removing any client access point that was created for the iSCSI Software Target server and uninstalling the product. This can be accomplished by using the following Windows PowerShell commands:

  1. To remove the resource groups:

    PS > Remove-ClusterGroup -Name <resource group name> -RemoveResources -Force
    
    
  2. To find the package GUID:

    PS > Get-WmiObject -Class Win32_product | Where-Object { $_.packageName –match 'iscsitarget'}
    
    
  3. To uninstall the package:

    PS > & msiexec /uninstall <Identifying Number > /qr
    
    

Retiring Microsoft iSCSI Software Target on your source server

Retiring Microsoft iSCSI Software Target 3.2 or iSCSI Software Target 3.3 on your source server requires using the following Windows PowerShell commands:

  1. To find the package GUID:

    PS > Get-WmiObject -Class Win32_product | Where-Object { $_.packageName –match 'iscsitarget'}
    
    
  2. To uninstall the package:

    PS > & msiexec /uninstall <Identifying Number > /qr
    
    

Retiring your source server

In a standalone configuration, there are no particular procedures for retiring the source server. In a clustered configuration, the client access points that are devoted to iSCSI Software Target access can be removed by using the following Windows PowerShell command:

PS > Remove-ClusterGroup -Name <resource group name> -RemoveResources -Force

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