Dynamic Disk Group Split and Join refers to two related commands - Split Dynamic Disk Group and Join Dynamic Disk Group. Split Dynamic Disk Group splits a dynamic disk group into two dynamic disk groups. Join Dynamic Disk Group joins two dynamic disk groups into one merged disk group. You can join two disk groups that were originally split apart with the Split Dynamic Disk Group command, but you can also join two dynamic disk groups that started out as separate disk groups.

Dynamic Disk Group Split and Join can be used for the FlashSnap process and to reorganize dynamic disk groups.

It can be implemented through the VEA console or through the command line by using the vxdg split and vxdg join commands.

With the Split Dynamic Disk Group command, you can take some but not all disks from one dynamic disk group to another. The source dynamic disk group retains its identity as the original, while the other dynamic disk group, called the target disk group, becomes a new dynamic disk group. After the split operation, the target dynamic disk group is in the Imported state if you used the GUI to implement the command. If you used the command line to do the split, the target dynamic disk group is by default in the Deported state (though you can use the -i switch to have it remain in the Imported state). In both the GUI and the command line, the source dynamic disk group continues to remain online after the split operation.

Primary dynamic disk groups cannot be split because primary dynamic disk groups usually contain the computer's boot and system disks. Also, only healthy dynamic volumes can be transferred in the split operation.

You can upgrade disk groups through the GUI.

You can also upgrade disk groups through the command line.

The Split Dynamic Disk Group command works on the premise that the split-off disk group should contain all disks that are needed to make the volumes in the new disk group complete. If the disks that you select to split the disk group result in incomplete volumes, the logic that is built into the command adds the remaining disk or disks needed to split the disk group with complete volumes. A screen is presented to you that lists the disks that are needed for the split. You can decide at that time whether you want to go ahead with the dynamic disk group split.

Thus, you are not able to split a dynamic disk group into two disk groups if any of the volumes that are allocated to either split disk group are incomplete.

The Join Dynamic Disk Group command lets you combine dynamic disk groups. It does not require that the dynamic disk groups to be joined were previously split. When you join two dynamic disk groups, the dynamic disk group you designate as the source becomes the one that loses its identity in the merge. The target dynamic disk group is the one that remains after the join.

With the join command, all the disks of the source dynamic disk group are joined with all the disks of the target dynamic disk group. Storage Foundation allows a partial join--that is, volumes in the source disk group can have missing or nonfunctional disks and the join command can still succeed. In this situation, you must click the Allow Partial Join check box to indicate that you want a partial join to take place. When the missing disk or disks come back to an online state, then you need to do another Join Dynamic Disk Group command to add the missing disk or disks to the target disk group.

The procedures in this section focus on the CLI commands that are related to Dynamic Disk Group Split and Join.

You can also perform Dynamic Disk Group Split and Join through the command line.