Creating a FlashCopy relationship

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Complete this task to create a FlashCopy® relationship between a source and target volume that enables a point-in-time copy of a source volume onto a target volume.

About this task

You can create a FlashCopy relationship between a source and a target volume that enables a point-in-time copy of a source volume onto a target volume. FlashCopy functions run on a DS8000® model and are supported on many operating systems. For example, if you set up and configure your machine to use i5/OS, you can create copies of System i® disk pools within a single machine using FlashCopy. After the FlashCopy function completes, you can immediately access the target point-in-time copies by associating another System i or logical partition.

When you enter a FlashCopy command with the background copy option, the FlashCopy relationship is established but it is put in a queue for background copying. The time difference between the submission and actual start time of the task depends on the number of FlashCopy relationships that are currently copying in the background or waiting in the queue. When the copy processing starts, the status displays as "background copy running" for that FlashCopy volume pair.

How long the actual physical copy processing takes can depend on the amount of data being copied and other activities that are occurring on the storage unit.

Note:

At the data set level, the maximum number of FlashCopy relationships allowed on a volume is 65534. If that number is exceeded, the FlashCopy operation fails.
With full volume FlashCopy, a source volume can be in FlashCopy and FlashCopy Space Efficient relationships with a maximum of 12 target volumes. If that number is exceeded, the FlashCopy operation fails. Of the up to 12 FlashCopy relationships, only one incremental FlashCopy relationship is allowed.
With FlashCopy Space Efficient, a source volume can be in FlashCopy and FlashCopy Space Efficient relationships with a maximum of 12 target volumes. If that number is exceeded, the FlashCopy operation fails.

You can complete this task using either the DS CLI or the DS8000 Storage Management GUI.

Complete the following steps to create FlashCopy relationships using the DS CLI commands. The example commands in this task are shown in two formats. The first format shows the type of information the command requires. The second format is an example command with declared values for the variables.

Procedure

Enter the mkflash command to create FlashCopy relationships.
dscli> mkflash -dev storage_image_ID sourcevolumeID:targetvolumeID

Example
```
dscli> mkflash -dev IBM.2107-75FA150 0001:0004
```
Notes:
1. Specify the storage unit for the -dev storage_image_ID parameter. 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. If the management console has an IP connection to the specified storage unit, the command works. If the IP connection is not established, you can use the mkremoteflash command if there is a PPRC Path established between the storage unit from which you enter the command and the (remote) storage unit where the FlashCopy volumes are located.
2. For further information, including optional parameters, see the mkflash and mkremoteflash commands.
A confirmation message is displayed for each successful FlashCopy pair that is created.
Enter the lsflash command to check the status information for each FlashCopy relationship. A detailed report (when you use the -l parameter) is displayed for each FlashCopy relationship.
dscli> lsflash -dev storage_image_ID -l SourceVolumeID:TargetVolumeID.
```
dscli> lsflash -dev IBM.2107-75FA150 -l 0100:0100
```
Use the-l parameter to provide a more detailed report about the FlashCopy relationships.
Note: If you used the mkremoteflash command, you must enter the lsremoteflash command to run a status check.