Using a FlashCopy volume in a 3DC multi-target configuration

You can use a FlashCopy^® T-VOL in a 3DC multi-target configuration. When a FlashCopy^® T-VOL is shared with a pair volume in a 3DC multi-target configuration, a FlashCopy^® relationship cannot be created depending on the combination of the URz and TCz pair status. The following table shows whether a FlashCopy^® T-VOL can be shared or not depending on the combination of the URz and TCz pair status in a 3DC multi-target configuration.

You should know the following:

• The data copied to the TCz P-VOL or URz P-VOL from the source volume of FlashCopy^® relationship is asynchronously copied with the initial copy operation to the TCz S-VOL or URz S-VOL. Based on the speed of the data copy processing to the TCz S-VOL or URz S-VOL, the synchronization rate of the TCz pair and URz pair is calculated. Depending on the copy processing order of the FlashCopy^® relationship, TCz pair, or URz pair, the time delay might be caused before the TCz or URz initial copy operation starts. In this case, the synchronization rate of the TCz or URz pair might slow.
• In a 3DC multi-target configuration using delta resync, at the creation or after the creation of a FlashCopy^® T-VOL, if a pair is in the Duplex status due to the pair resync operation in TCz or URz, a journal for a differential resync operation cannot be created, and therefore all data is copied even if the differential resync operation is performed.

When a FlashCopy^® T-VOL is used in a 3DC multi-target configuration, before performing the FlashCopy^® copy operation, make sure to suspend either the URz or TCz pair. To do this, use the following workflow. If the Preserve Mirror FlashCopy^® function is used, there are no restrictions. For more information, see the TrueCopy^® for Mainframe User Guide or the Universal Replicator for Mainframe User Guide.