reverseflash

Parameters

You can reverse the direction of a FlashCopy relationship, where the volume that was previously defined as the target becomes the source for the volume that was previously defined as the source. The data that has changed is copied to the volume that was previously defined as the source. For example, 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.

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

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

-dev storage_image_ID

(Optional) The storage image ID consists of the manufacturer name, machine type, and serial number. The storage image ID is required if you do not specify a fully qualified ID for the source and target volumes, do not set the devid variable in your profile or through the setenv command, and the HMC is aware of more than one storage image. Using the -dev parameter will temporarily override any defined value for devid for the current command. For example, storage system models use IBM.2107-75FA120

-record

(Optional) This parameter, without the -multinc parameter, creates a type 1 incremental FlashCopy relationship. The type 1 FlashCopy® records data changes on both the source and target volumes of the FlashCopy pair.

A single volume can be the source volume to up to 12 FlashCopy relationships, and these relationships can be any combination of normal, persistent, or incremental relationships. However, only a single type 1 incremental relationship can exist.

Select this parameter when you create an initial FlashCopy relationship that you later want to use with the resyncflash or reverseflash command. If the -multinc parameter is not selected, you can also use the setflashrevertible command.

When you select the -record parameter, the –persist parameter is automatically selected.

-persist

(Optional) Creates a persistent FlashCopy relationship in which the relationship remains after the copy completes and remains indefinitely until you enter a rmflash command against the FlashCopy pair. If this parameter is not specified, a normal FlashCopy relationship is created and is automatically removed after the copy completes.

A single volume can be the source volume to up to 12 FlashCopy relationships, and these relationships can be any combination of normal, persistent, or incremental relationships. However, only a single type 1 incremental relationship can exist.

See the -record parameter for a description of a type 1 incremental FlashCopy relationship and the -multinc parameter for a description of a type 2 incremental relationship.

When you select either the -record or the -multinc parameter, the persist parameter is automatically selected.

-multinc

(Optional) Creates a type 2 incremental FlashCopy relationship. The type 2 FlashCopy records data changes only on the target volume of the FlashCopy pair.

A single volume can be the source volume to up to 12 FlashCopy relationships, and these relationships can be any combination of normal, persistent, or incremental relationships. However, only a single type 1 incremental relationship can exist.

The type 2 FlashCopy allows for more than one incremental FlashCopy relationship from the same source volume. However, because the change recording is maintained only on the target volume, the type 2 FlashCopy can cause a performance impact as more type 2 FlashCopy relationships are added.

Select this parameter when you create multiple FlashCopy volume pairs with the same source volume that you want to use with the resyncflash and reverseflash commands. However, FlashCopy pairs established with this modified recording method cannot be used with the setflashrevertible command.

When you select the -multinc parameter, the -persist and -record parameters are automatically selected.

-fast

(Optional) Use this parameter when you want to process the reverseflash command 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, the original FlashCopy target volume is not usable. Normally, after this command completes the background copy, the new FlashCopy target volume is used as the FlashCopy source volume to restore the original FlashCopy target volume.

-tgtpprc

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

-tgtoffline

(Optional) Rejects the reverseflash command if the target volume is online for host system access. This parameter applies only to count key data (CKD) volumes.

-tgtinhibit

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

-tgtse

(Optional) The target volume that you are designating for a FlashCopy relationship might be a space-efficient logical volume. An error message is generated if the target volume that you are using to create the FlashCopy relationship is a space-efficient volume and you do not specify this parameter.

-nocp

(Optional) Inhibits a background copy. Data is copied from the source volume to the target volume only if a track on the source volume is modified. The FlashCopy volume pair relationship remains indefinitely until it is broken by a rmflash command or until all tracks on the source volume are modified.

If neither the -cp nor the -nocp parameter are specified, then the default background copy behavior is determined by the -tgtse and -fast parameters. If the -tgtse parameter is specified, and the -fast parameter is not specified, then the default behavior is to not perform a background copy. Otherwise, the default behavior is to perform a background copy.

Note: You cannot use the -nocp parameter with the -cp parameter in the same command.

-cp

(Optional) Starts a background copy. Data is copied from the source volume to the target volume as a background task and does not require any source volume modifications to trigger the copy.

If neither the -cp nor the -nocp parameter are specified, then the default background copy behavior is determined by the -tgtse and -fast parameters. If the -tgtse parameter is specified, and the -fast parameter is not specified, then the default behavior is to not perform a background copy. Otherwise, the default behavior is to perform a background copy.

Note: You cannot use the -nocp parameter with the -cp parameter in the same command.

-seqnum flash_sequence_num

(Optional)Associates the FlashCopy relationships that are established with the specified sequence number. You can use this sequence number as an identifier for a relationship or group of relationships. An example sequence number is 00010.

-pmir no | required | preferred

The Remote Pair Copy option that you want to use. The Remote Pair Copy option, sometimes called Preserve Mirror, preserves synchronous Metro Mirror pairs when the FlashCopy source volume and target volume are Metro Mirror primary volumes and the Metro Mirror secondary volumes are on the same storage system. The FlashCopy operation is performed on both the local site and the remote site.

no

FlashCopy operations are not performed on the remote site. If the target volume is a Metro Mirror primary volume, the remote copy might temporarily change to the duplex pending state. The default is no if the -pmir parameter is not specified.

required

FlashCopy operations do not change the state of the Metro Mirror primary volume pair to duplex pending. Both the source Metro Mirror volume pair and the target Metro Mirror volume pair must be in the full duplex state.

preferred

Uses the Remote Pair Copy option for FlashCopy operations when possible. The Remote Pair Copy option cannot be used if the configuration is not correct or the state of the volume is not supported with this function.

Notes:

• The -preferred parameter is only valid for DS8870 and earlier system types.
• The -preferred parameter is not valid for targets which are also PPRC multi-target primaries.

-resetreserve

(Optional) Forcibly clears any SCSI reservation on the target volume and allows establishing of a FlashCopy relationship. The reservation is not restored after the relationship is established.

• When this option is not specified and the target volume is reserved, the command fails.
• This option is ignored if the target is a CKD volume; this option is applicable only for fixed block volumes.

source_volume_ID:target_volume_ID ... | -

(Required) Establishes a FlashCopy relationship for the source and target volume pairs with the specified IDs. This parameter accepts fully qualified volume IDs, which consist of storage image IDs or a shortened version without storage image IDs, if the -dev parameter is specified. You can also 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

The address group, 0 - F.

XY

The logical subsystem number, 00 - FE.

ZZ

The volume number, 00 - FF.

The ellipsis (...) indicates that, optionally, you can specify multiple values. If you use the dash (-), the specified value is read from standard input. You cannot use the dash (-) while you are in the DS CLI interactive command mode.

An example of a fully qualified FlashCopy pair ID is IBM.2107-75FA120/0001:IBM.2107-75FA120/0004

An example of a shortened version is 0001:0004

An example of multiple pairs is 0001:0004 0003:00FF 0008:000C