FlashCopy mapping events

FlashCopy® mapping events detail the events that modify the state of a FlashCopy mapping.

Table 1 provides a description of each FlashCopy mapping event.
Table 1. FlashCopy mapping events
Event Description
Create A new FlashCopy mapping is created between the specified source volume and the specified target volume. The operation fails if any of the following situations is true:
  • The source volume is already a member of 256 FlashCopy mappings.
  • The node has insufficient bitmap memory.
  • The source and target volumes are different sizes.
Prepare The prepare command is directed to either a consistency group for FlashCopy mappings that are members of a normal consistency group or to the mapping name for FlashCopy mappings that are stand-alone mappings. The prepare command places the FlashCopy mapping into the preparing state.
Attention: The prepare command can corrupt any data that previously resided on the target volume because cached writes are discarded. Even if the FlashCopy mapping is never started, the data from the target might logically change during the act of preparing to start the FlashCopy mapping.
Flush done The FlashCopy mapping automatically moves from the preparing state to the prepared state. This is done after all cached data for the source is flushed and all cached data for the target is no longer valid.
Start When all the FlashCopy mappings in a consistency group are in the prepared state, the FlashCopy mappings can be started.

To preserve the cross volume consistency group, the start of all of the FlashCopy mappings in the consistency group must be synchronized correctly regarding I/Os that are directed at the volumes. This alignment is achieved during the start command.

The following series of events occurs during the start command:
  • New reads and writes to all source volumes in the consistency group are paused in the cache layer until all ongoing reads and writes below the cache layer are completed.
  • After all FlashCopy mappings in the consistency group are paused, the internal clustered system state is set to allow FlashCopy operations.
  • After the system state is set for all FlashCopy mappings in the consistency group, read and write operations are unpaused on the source volumes.
  • The target volumes are brought online.

As part of the start command, read and write caching is enabled for both the source and target volumes.
Modify The following FlashCopy mapping properties can be modified:
  • FlashCopy mapping name
  • Clean rate
  • Consistency group
  • Copy rate (for background copy or stopping copy priority)
  • Automatic deletion of the mapping when the background copy is complete
Stop There are two separate mechanisms by which a FlashCopy mapping can be stopped:
  • You issue a command
  • An I/O error occurs
Delete This command requests that the specified FlashCopy mapping is deleted. If the FlashCopy mapping is in the stopped state, the force flag must be used.
Flush failed If the flush of data from the cache cannot be completed, the FlashCopy mapping enters the stopped state.
Copy complete After all of the source data is copied to the target and there are no dependent mappings, the state is set to copied. If the option to automatically delete the mapping after the background copy completes is specified, the FlashCopy mapping is automatically deleted. If this option is not specified, the FlashCopy mapping is not automatically deleted and can be reactivated by preparing and starting again.
Bitmap Online/Offline The node fails.