Note: When you implement Global Mirror, you setup the FlashCopy between the B and C volumes with No Background copy and Start Change Recording options. It means that
before the latest data is updated to the B volumes, the last consistent data in the B volume is moved to the C volumes. Therefore, at some time, a part of consistent data is in the B volume, and the other part of consistent data is in the C volume.
If a disaster occurs during the FlashCopy of the data, special procedures are needed to finalize the FlashCopy.
In the recovery phase, the consistent copy is created in the B volumes. You need some operations to check and create the consistent copy.
You need to check the status of the B volumes for the recovery operations. Generally, these check and recovery operations are complicated and difficult with the GUI or CLI in a disaster situation. Therefore, you may want to use some management tools (for example, Global Mirror Utility), or management software (for example, Multiple Device Manager Replication Manager), for Global Mirror to automate this recovery procedure.
The data at the remote site is current within 3 to 5 seconds, but this recovery point (RPO) depends on the workload and bandwidth available to the remote site.
In contrast to the previously mentioned Global Copy solution, Global Mirror overcomes its disadvantages and automates all of the steps that have to be done manually when using Global Copy.
If you use Global Mirror, you must adhere to the following additional rules:
You must purchase a
If Global Mirror will be used during failback on the secondary storage unit, you must also purchase a
Note: PPRC can do failover and failback operations. A failover operation is the process of temporarily switching production to a backup facility (normally your recovery site) following a planned outage, such as a scheduled maintenance period, or an unplanned outage, such as a disaster. A failback operation is the process of returning production to its original location. These operations use Remote Mirror and Copy functions to help reduce the time that is required to synchronize volumes after the sites are switched during a planned or unplanned outage.
z/OS Global Mirror (XRC)
z/OS Global Mirror is an asynchronous copy function for the z/Series environment. This function has a different architecture than Global Mirror. The DS6000 can only be used as a secondary system for z/OS Global Mirror (it cannot be used as primary system).
102DS6000 Series: Concepts and Architecture
