Asynchronous Copy Services
IntelliMagic Vision provides sizing and analysis capabilities for the Asynchronous Copy Services implementations from all the vendors: IBM's Global Mirror, EMC's SRDF/A, HP's Continuous Access Asynchronous and Journal, and HDS TrueCopy/Async and Universal Replicator.
Bandwidth sizing based on existing data is supported for these implementations, with analysis capabilities specific for each platform. With Asynchronous data mirroring, an installation can deliberately configure less bandwidth than what is needed in the peak intervals, accepting that this will have an impact on the currency of the secondary data image: the target of how far the secondary data image will run behind on the primary data image may be willingly compromised during a certain period of the day, for instance during the batch hours.
With IntelliMagic Vision, the user can define the amount of bandwidth available (the yellow line in the chart) and will then be presented with information about how long the secondary delay will be over target (the blue line). This allows the capacity planner to see when and for how long delays would occur such that it is possible to take a well-informed decision about the bandwidth needed for this specific I/O load.
Asynchronous data mirroring as implemented in IBM’s Global Mirror and EMC’s SRDF/A, operates in cycles. This may have an impact for the amount of bandwidth needed to mirror the data since only the last update of a record within an interval needs to be transmitted to the secondary disk subsystem. RMF Magic computes the amount of write activity (expressed in MB /sec) for those devices that will be part of the data mirroring configuration (the white line in the chart below) and the amount of data that would have to be transmitted (the purple line). Note that for this particular I/O load there is little difference between the two lines.
