reverseflash

Parameters

The direction of a FlashCopy relationship can be reversed, where the volume that was previously defined as the target becomes the source for the volume that was previously defined as the source (and is now the target). The data that has changed is copied to the volume that was previously defined as the source. For example, suppose you create a FlashCopy relationship between source volume A and target volume B. Data loss occurs on source volume A. To keep applications running, you can reverse the FlashCopy relationship so that volume B is copied to volume A.

The source volume and the target volume that are specified by this command are the current source and target volumes that, as a result of this command process, become reversed. The specified target volume becomes the source and the specified source volume becomes the target. The target parameters specified by this command apply to the new target (the source volume that becomes the target volume when this command is processed).

After the reversal takes place, ensure that you designate this new relationship when you issue any future commands. Failure to designate this reversed relationship could produce unexpected results. For example, you reverse the relationship of source volume 1600 and target volume 1800. Using the reverseflash command, your source volume becomes 1800 and your target volume become 1600. All queries and future processing on this relationship must show volume 1800 as your source and volume 1600 as your target.

The following list defines the parameters that are associated with the reverseflash command:

-dev storage_image_ID

(Optional) Specifies the storage image ID, which includes manufacturer, machine type, and serial number. This parameter is required if you do not specify a fully qualified ID for the source and target volumes and you do not specify a value for the devid variable in your profile file.

Example: IBM.1750-75FA120

-record

(Optional) Records the changed tracks on both volumes within a FlashCopy pair. Use this parameter when you establish an initial FlashCopy volume pair that you intend to use with the resyncflash command. The -persist parameter is automatically designated when the -record parameter is selected.

-persist

(Optional) Retains the FlashCopy relationship after the background copy completes. The FlashCopy relationship between the source and the target volumes remains indefinitely until it is broken by a rmflash command. This parameter is automatically designated when the -record parameter is specified. Select the -persist parameter along with the -record parameter if you are using this volume pair with the resyncflash, reverseflash, or setflashrevertible commands.

-fast

(Optional) Specify this parameter when the reverseflash command will be issued before the background copy completes.

Note: To use the fast reverse function, the relationship must be set to Target write inhibit. The fast reverse processing function is intended for use as part of Global Mirror recovery process.

At the end of this operation (processing the reverseflash command with the -fast parameter), the original FlashCopy target volume is unusable. Normally, after this command completes the background copy, the new FlashCopy target is used as FlashCopy source to restore the original FlashCopy target.

-tgtpprc

(Optional) Allows the FlashCopy target volume to be a Remote Mirror and Copy source volume.

-tgtoffline

(Optional) Causes the reverseflash command to be rejected if the target volume is online for host system access. This parameter only applies to CKD volumes.

-tgtinhibit

(Optional) Prevents host system write operations to the target while the FlashCopy relationship exists.

-seqnum flash_sequence_num

(Optional) Associates the FlashCopy relations that are reversed with the specified sequence number. Only the relations that are successfully modified by the command receive the specified sequence number, leaving the ones that failed with the previous number (if previously specified). The sequence number is a four-digit hexadecimal number (0000 - FFFF). The default is 0000.

Example: 0010

This parameter is not supported for machine type 2105.

source_volume_ID:target_volume_ID . . . | -

(Required) Reverses a FlashCopy relationship for the source and target volume pairs with the specified IDs. This parameter accepts fully qualified volume IDs, which includes storage image IDs, or a shortened version without storage image IDs if the -dev parameter is specified or you specify a value for the devid variable in your profile file. You must separate multiple FlashCopy pair IDs with spaces.

A FlashCopy pair ID consists of two volume IDs, one designated as the source and the other as the target volume for a FlashCopy relationship. You must separate the two volume IDs of a FlashCopy pair ID with a colon and no space. The first volume ID is the source volume. The second volume ID is the target volume.

The volume ID is a 32 bit number that can be represented as 4 hexadecimal digits in the form of XYZZ where X is the address group (0 - 1), XY together is the logical subsystem number 00 - 1E (for 1750) , and ZZ is the volume number (00 - FF).

If you specify the dash (-), this parameter information is automatically supplied.

Example of a fully qualified FlashCopy pair ID: IBM.1750-68FA120/0001:IBM.1750-68FA120/0004

Example of a shortened version: 0001:0004

Example of multiple pairs: 0001:0004 0003:00FF 0008:000C