Creating an image mode VDisk

You can import storage that contains existing data and continue to use this storage but make use of the cache and advanced functions, such as Copy Services and data migration. These disks are known as image mode virtual disks (VDisks).

Make sure that you are aware of the following before you create image mode VDisks:

Unmanaged-mode managed disks (MDisks) that contain existing data cannot be differentiated from unmanaged-mode MDisks that are blank. Therefore, it is vital that you control the introduction of these disks to the cluster. It is recommended that you introduce these disks one at a time. For example, map a single logical unit from your RAID controller to the cluster and refresh the view of MDisks. The newly detected disk is displayed.
Do not manually add an unmanaged-mode MDisk that contains existing data to an MDisk group. If you do, the data is lost. When you use the command to convert an image mode VDisk from an unmanaged-mode disk, select the MDisk group where you want to add the VDisk.

See the following Web site for more information:

www.ibm.com/storage/support/2145

This task assumes that you have already launched the SAN Volume Controller Console.

Perform the following steps to create an image mode VDisk:

Stop all I/O operations from the hosts.
Unmap the logical disks that contain the data from the hosts.
Perform the following steps to create one or more MDisk groups:
1. Click Work with Managed Disks > Managed Disk Groups in the portfolio. The Viewing Managed Disk Groups panel is displayed.
2. Select Create an MDisk Group from the task list and click Go. The Create Managed Disk Group wizard begins.
3. Use the wizard to create the MDisk group.
Perform the following steps to convert the unmanaged-mode MDisk to an image mode VDisk:
1. Click Work with Managed Disks > Managed Disks in the portfolio. The Viewing Managed Disks panel is displayed.
  If the new unmanaged-mode MDisk is not listed, you can perform a fabric-level discovery. Select Discover MDisks from the task list and click Go. When this process is complete, refresh the list of MDisks, and the unmanaged-mode MDisk should appear in the list.
2. Select the unmanaged-mode MDisk and select Create VDisk in Image Mode from the task list. Click Go. The Create Image mode Virtual Disk wizard begins.
  Note: If the VDisk that you are creating maps to a solid-state drive (SSD), the data that is stored on the VDisk is not protected against SSD failures or node failures. To avoid data loss, add a VDisk copy that maps to an SSD on another node.
3. Use the wizard to select the MDisk group where the image mode VDisk should be added and the I/O group that will provide the data path for the VDisk.
Perform the following steps to map the new VDisk to the hosts that were previously using the data that the MDisk now contains:
1. Click Work with Virtual Disks > Virtual Disks in the portfolio. The Viewing Virtual Disks panel is displayed.
2. Select the VDisks and select Map VDisks to a host from the task list. Click Go. The Creating Virtual Disk-to-Host Mappings panel is displayed.
3. Select the host that you want to map the VDisk to and click OK.

After the image mode VDisk is mapped to a host object, it is detected as a disk drive with which the host can perform I/O operations.

If you want to virtualize the storage on an image mode VDisk, you can transform it into a striped VDisk. Migrate the data on the image mode VDisk to managed-mode disks in another MDisk group.