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# Expand CKD volumes

Unisphere supports the expansion of CKD volumes.

## Prerequisites

See Roles and associated permissions to determine the user roles that can perform this task.

You can expand a volume up to 1,182,006 cylinders (1 TB). To expand a device above 565,250 cylinders, the new size must be a multiple of 1113 cylinders. If you specify a size that is not that multiple, the system rounds the size up to the next multiple of 1113.

You cannot expand a volume when it is:

- A CKD 3380 device
- A TDAT
- Marked as Soft Fenced
- Part of aN SRDF session
- Part of a SnapVX session

The following procedure describes one way to expand a CKD volume. You can also carry out this task from Storage > Storage Groups > Volumes or Storage > Volumes.

## Steps

1. Select the storage system.
2. Click Hosts > Mainframe, click CKD Volumes, select a volume, and click Expand to open the Expand Volume dialog.
3. In the Volume Capacity field of the Expand Volume dialog box, type or select the new capacity of the volume. The Total Capacity and Additional Capacity figures update automatically.

   | NOTE: In 10.1.0.0, there has been a change in the rounding of GB/TB/MB to cylinders when creating or expanding a volume. Creating or expanding a volume in TB/GB/MB in some scenarios results in a volume slightly smaller or slightly larger than if you had created the same size volume in TB/GB/MB in release 10.0, for example, creating a 2TB vol is 1118481 Cyl in 10.1.0.0 , but in 10.0 a 2TB vol is 1118482 Cyl). If you want to create a volume in 10.1.0.0 and need to guarantee that it exactly matches the size of a volume that was created using 10.0, you must specify the volume size in Cylinders and not TB/GB/MB when creating or expanding.

4. To reserve the volume, select Reserve Volumes.
5. Do one of the following:
   - Click Run Now to perform the operation now.
   - Expand Run Now and click Add to Job List to add this task to the job list, from which you can schedule or run the task at your convenience. For more information, see Schedule jobs and Preview jobs.