Dell PowerStore Importing External Storage to PowerStore Guide

Overview of the non-disruptive import process

Before importing the external storage from a source system to a PowerStore cluster, the active path for the host I/O is to the source system. During the setup of import, the host or hosts build an inactive I/O path to the volumes that are created on the PowerStore cluster which match the specified volumes on the source system. When you start import, the active host I/O path to the source system becomes inactive and the inactive host I/O path to the PowerStore cluster becomes active. However, the source system is kept updated through the I/O forwarding from the PowerStore cluster. When the import reaches the Ready For Cutover state and you initiate cutover, the host I/O path to the source system is removed and the host I/O is directed only to the PowerStore cluster.

Review the following processes to gain an understanding of the import procedure:

1. Preconfigure – Set up the network connectivity.
   • The connection between an existing Dell PS Series or Dell SC Series source system and the PowerStore cluster must be over iSCSI.
   • For Dell PS Series or Dell SC Series source systems – All the connections between the hosts and the Dell PS Series or Dell SC Series source system and between the hosts and the PowerStore cluster must be over iSCSI.
   • The connection between an existing Dell Unity Series or Dell VNX2 Series source system and the PowerStore cluster can be over either iSCSI or Fibre Channel (FC). See the PowerStore Simple Support Matrix document at https://www.dell.com/powerstoredocs to determine which protocol to use.
   • For Dell Unity Series or Dell VNX2 Series source systems – The connections between the hosts and the Dell Unity Series or Dell VNX2 Series source system and between the hosts and the PowerStore cluster must be either all over iSCSI or all over Fibre Channel (FC) and match the connection between the source system and the PowerStore cluster. See the PowerStore Simple Support Matrix document at https://www.dell.com/powerstoredocs to determine which protocol can be used. Also, all host initiators that are connected to the source system should also be connected to the PowerStore cluster.
     NOTE:When FC connectivity between the hosts and the source system, the hosts and the PowerStore cluster, and source system and the PowerStore cluster is used, the administrator must set up FC zoning between the hosts, the source system, and the PowerStore cluster.
2. Setup import – Install or upgrade the appropriate host plugin as needed on each host that accesses the storage to be imported. Add the source system to the PowerStore cluster, if it is not already listed. Select one or more volumes or consistency groups, or both to be imported. A volume group cannot be combined with any other volumes or volume group. Select to add the hosts that access the storage to be imported, the hosts build inactive I/O paths to the destination volumes. Set the import schedule and assign protection policies.
3. Start import – A destination volume is created for each selected source volume. A volume group is automatically created for each consistency group that is selected for import. The active I/O and inactive I/O paths from the host are switched to redirect the I/O to the PowerStore cluster. However, the source is kept updated through the I/O forwarding from the PowerStore cluster.
4. Cutover import – Cutover can be performed only when the import processing state is Ready For Cutover. In other words, cutover is a final confirmation. You can select to cut over automatically without user intervention. After the cutover step, I/O cannot go back to the source system volume.

In addition, the following processes are available during the import procedure:

• Pause import – Pause can be performed when the import processing state is Copy In Progress. When an import session is paused, only the background copy is stopped. The forwarding of host I/O to the source system continues to be active.
  NOTE:The Pause import action on a CG only pauses the member volumes that are in the Copy In Progress state. The CG remains in the In Progress state. Other member volumes that are in other states, such as Queued or In Progress, are not paused and may proceed to the Ready For Cutover state. The other member volumes can be paused when they reach the Copy In Progress state by using the Pause import action again on the CG. If any of the member volumes are in the Paused state but the overall status of the CG is In Progress, both the Pause and Resume import action options are available for the CG.
• Resume import – Resume can be performed when the import processing state is Paused.
• Cancel import – Cancel can be performed only when the import processing state is Copy In Progress (for volume), In Progress (for consistency group), Ready For Cutover, Queued, Paused (for volume), or Scheduled, or Cancel Failed (for consistency group). Cancel allows you to cancel the import process with the click of a button and change the active path back to the source.

For Dell PS Series source systems only – The source volume is taken offline after a successful cutover operation.

For the Dell SC Series, Dell Unity Series, and Dell VNX2 Series source systems – Host access to the source volume is removed after a successful cutover operation.