You can use the command-line interface (CLI) to import
storage that contains existing data and continue to use this storage.
You can also the advanced functions, such as Copy Services, data migration,
and the cache. These disks are known as image mode virtual disks (VDisks).
Make sure 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
MDisks to the cluster by adding these disks one at a time. For example,
map a single LUN from your RAID controller to the cluster and refresh
the view of MDisks. The newly detected MDisk 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, you will select the MDisk group where it should be added.
See the following Web site for more information:
www.ibm.com/storage/support/2145
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.
- Create one or more MDisk groups.
- Map a single RAID array or logical unit from your RAID
controller to the cluster. You can do this through a switch zoning
or a RAID controller based on your host mappings. The array
or logical unit appears as an unmanaged-mode MDisk to the SAN Volume Controller.
- Issue the svcinfo lsmdisk command to list the unmanaged-mode
MDisks.
If the new unmanaged-mode MDisk is not listed,
you can perform a fabric-level discovery. Issue the
svctask detectmdisk command
to scan the fibre-channel network for the unmanaged-mode MDisks.
Note: The svctask
detectmdisk command also rebalances MDisk access across the available
controller device ports.
- Convert the unmanaged-mode MDisk to an image mode virtual
disk.
Note: If the VDisk
that you are converting 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.
Issue the svctask mkvdisk command to create
an image mode virtual disk object.
- Map the new VDisk to the hosts that were previously using
the data that the MDisk now contains. You can use the svctask
mkvdiskhostmap command to create a new mapping between a VDisk
and a host. This makes the image mode VDisk accessible for I/O operations
to the host.
After the VDisk is mapped to a host object, the VDisk 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. Issue
the svctask migratevdisk command to migrate an entire image
mode VDisk from one MDisk group to another MDisk group.