Learn About Virtual Disk Copy

Caution: Possible Loss of Access to Data. participating in a virtual disk copy are available for read I/O activity only while a virtual disk copy has a status of In Progress or Pending. Write requests are allowed after the virtual disk copy has completed.

If the source virtual disk has been formatted with a journaling filesystem, any attempt to issue a read request to the source virtual disk might be rejected by the , and an error message may be displayed. The journaling filesystem driver will issue a write request before it attempts to issue the read request. The RAID controller module will reject the write request, and the read request may not be issued due to the rejected write request. This may result in an error message being displayed, indicating that the source virtual disk is write protected.

To prevent this issue from occurring, do not attempt to access a source virtual disk participating in a virtual disk copy while the virtual disk copy has a status of In Progress. Also, ensure that read-only attribute for the is disabled after the virtual disk copy has completed to prevent error messages from being displayed.

The Virtual Disk Copy is used to copy data from one (the ) to another virtual disk (the ) in a single storage array. This feature can be used to copy data from that use smaller capacity physical disks to disk groups that use larger capacity physical disks, to back up data, or to restore data to the source virtual disk. This premium feature includes a Create Copy Wizard, to assist in creating a virtual disk copy, and a Copy Manager, to monitor virtual disk copies after they have been created.

The Virtual Disk Copy Premium Feature must be enabled by purchasing a ??from your storage vendor. The following table briefly describe some applications for the Virtual Disk Copy Premium Feature.

Copying Data for Greater Access	As your storage requirements for a virtual disk change, the Virtual Disk Copy Premium Feature can be used to copy data to a virtual disk in a disk group that utilizes larger capacity disk physical disks within the same storage array. This provides an opportunity to move data to larger physical disks (for example, 73 GB to 146 GB), change to physical disks with a higher data transfer rate (for example, 1 Gb/s to 2 Gb/s), or to change to physical disks using new technologies for higher performance.
Backing Up Data	The Virtual Disk Copy Premium Feature allows you to create a backup of a virtual disk by copying data from one virtual disk to another virtual disk in the same storage array. The target virtual disk can be used as a backup for the source virtual disk, for system testing, or to back up to another storage array, such as a tape physical disk.
Restoring Snapshot Virtual Disk Data to the Source Virtual Disk	If you need to restore data to the source virtual disk from its associated snapshot virtual disk, the Virtual Disk Copy Premium Feature can be used to copy the data from the snapshot virtual disk to the source virtual disk. You can create a virtual disk copy of the data on the snapshot virtual disk, then copy the data to the source virtual disk.

Before You Begin

A virtual disk copy will fail all snapshot virtual disks associated with the target virtual disk, if any exist. If you select a of a snapshot virtual disk, you must disable all associated with the source virtual disk before you can select it as a target virtual disk. Otherwise, the source virtual disk cannot be used as a target virtual disk.

A virtual disk copy overwrites data on the target virtual disk and automatically makes the to .

If there are eight virtual disk copies with a status of In Progress, any subsequent virtual disk copy will have a status of Pending until one of the eight virtual disk copies completes.

Virtual Disk Copy and Modification Operations

If a is running on a source virtual disk or target virtual disk, and the virtual disk copy has a status of In Progress, Pending, or Failed, then the virtual disk copy will not take place. If a modification operation is running on a source virtual disk or target virtual disk after a virtual disk copy has been created, then the modification operation must complete before the virtual disk copy can start. If a virtual disk copy has a status of In Progress, then any modification operation will not take place.

Create Copy Wizard

The Create Copy Wizard guides you through the process of selecting a source virtual disk from a list of available virtual disks, selecting a target virtual disk from a list of available virtual disks, and setting the for the virtual disk copy. When you have completed the Wizard dialogs, the virtual disk copy starts and data is read from the source virtual disk and written to the target virtual disk.

Operation in Progress icons are displayed on the source virtual disk and target virtual disk while the virtual disk copy has a status of In Progress or Pending.

Refer to the restrictions section for more information about source virtual disks and target virtual disks.

Failed Virtual Disk Copy

A virtual disk copy can fail because of a read error from the source virtual disk, a write error to the target virtual disk, or because of a failure on the storage array that affects the source virtual disk or target virtual disk (such as a ). A critical event is logged in the when the virtual disk copy fails, and a Needs-Attention icon is displayed in the . While a virtual disk copy has this status, the host has read-only access to the source virtual disk, and read and write requests to the target virtual disk will not take place until the failure is corrected by using the Recovery Guru.

Preferred RAID Controller Module Ownership

During a virtual disk copy, the same RAID controller module must own both the source virtual disk and target virtual disk. If both virtual disks do not have the same preferred RAID controller module when the virtual disk copy starts, the ownership of the target virtual disk is automatically transferred to the preferred RAID controller module of the source virtual disk. When the virtual disk copy is completed or is stopped, ownership of the target virtual disk is restored to its preferred RAID controller module. If ownership of the source virtual disk is changed during the virtual disk copy, ownership of the target virtual disk is also changed.

Failed RAID Controller Module

must be manually changed to the alternate RAID controller module to allow the virtual disk copy to complete under the following conditions:

If a virtual disk copy has a status of In Progress, and
Its preferred RAID controller module fails, and
The ownership transfer does not occur automatically in the failover

Refer to Changing RAID Controller Module Ownership of a Disk Group for procedures and more information.

Copy Manager

After you create a virtual disk copy with the Create Copy Wizard, the virtual disk copy can be monitored through the . From the Copy Manager, a virtual disk copy might be re-copied, stopped, or removed, and its attributes, including the copy priority and the target virtual disk Read-Only attribute, can be modified. The status of a virtual disk copy can be viewed in the Copy Manager. Also, if you need to determine what virtual disks are involved in a virtual disk copy, use the Copy Manager or the .

Set the Target Virtual Disk Read-Only Attribute

This option determines how read and write requests to the target virtual disk are handled after a virtual disk copy is complete or if the virtual disk copy fails prior to completing. After the virtual disk copy is complete, the target virtual disk automatically becomes read-only to hosts, and write requests to the target virtual disk will not take place. When the attribute for a target virtual disk is enabled, a lock icon is displayed in the Target Virtual Disk column of the Copy Manager. The Read-Only attribute can be changed in the Copy Manager only after the virtual disk copy is completed.

Re-Copy a Virtual Disk

This option allows you to create a new virtual disk copy of the data on a selected . Re-Copy can be used to create a new virtual disk copy from the beginning if the original virtual disk copy fails or was stopped. You can also use this option for backup purposes; for instance, if the data on the source virtual disk changes, you can use Re-Copy to duplicate any new data to the target virtual disk.

Stop a Virtual Disk Copy

This option can stop a virtual disk copy with a status of Pending, In Progress, or Failed. If you decide not to use a particular virtual disk as a source virtual disk or target virtual disk, you can use this option to stop the virtual disk copy before it completes. The virtual disks can then be used in a new virtual disk copy. Using this option on a virtual disk copy with a status of Failed will clear the Needs-Attention condition on the storage array.

Change Copy Priority

This option is used to balance I/O activity with virtual disk copy activity on a storage array. You can set the copy priority to a rate that will have the least impact on I/O activity. There are five copy priority rates available: lowest, low, medium, high, and highest. If the copy priority is set at the lowest rate, I/O activity is prioritized and the virtual disk copy will take longer. If the copy priority is set to the highest priority rate, the virtual disk copy is prioritized, but I/O activity for the storage array might be affected.

Remove Copy Pairs

This option allows you to remove a virtual disk copy from the Copy Manager. After the virtual disk copy is removed, the source virtual disk and target virtual disk can be used in a new virtual disk copy. When the virtual disk copy is removed, the Read-Only attribute for the target virtual disk is also removed.

Restrictions

Important: If the source virtual disk is a , the target virtual disk capacity must be equal to or greater than the of the source virtual disk.

Important: If you choose a source virtual disk of a snapshot virtual disk as your target virtual disk, you must disable all snapshot virtual disks associated with the source virtual disk before you can select it as a target virtual disk. Otherwise, the source virtual disk cannot be used as a target virtual disk.

The following restrictions apply to the source virtual disk, target virtual disk, and the storage array:

The source virtual disk is available for read I/O activity only while a virtual disk copy has a status of In Progress or Pending. Write requests are allowed after the virtual disk copy is completed.
A virtual disk can be used as a target virtual disk in only one virtual disk copy at a time.
The maximum allowable number of virtual disk copies per storage array is dependent upon the number of target virtual disks available on your storage array.
A storage array can have up to eight virtual disk copies running at any given time.
The target virtual disk capacity must be equal to or greater than the source virtual disk capacity.
A source virtual disk can be a , , , or a .
A target virtual disk can be a standard virtual disk, a source virtual disk of a disabled or failed snapshot virtual disk, or a Remote Virtual Disk Mirror primary virtual disk.

Virtual Disks that have the following statuses cannot be used as a source virtual disk or target virtual disk:

A virtual disk that is reserved by the host cannot be selected as a source or target virtual disk.
A virtual disk that is in a .
A virtual disk that is the source virtual disk or target virtual disk in another virtual disk copy with a status of Failed, In Progress, or Pending.
A virtual disk with a status of Failed.
A virtual disk with a status of .