Process type
IMS HP Image Copy supports two types of image copy processes: the standard image copy process and the Advanced Image Copy Services process.
Choose a process type based on these factors: the duration that IMS HP Image Copy accesses the database, the amount of system resources, and performance.
Standard image copy process
With this process, to reduce the CPU workload and EXCP (execute channel program) counts, the Image Copy function can optionally use the High Performance Input/Output (HPIO) interface to access database data sets. Also, the internal storage and buffers that are used in the image copy job can be automatically optimized to achieve improved performance over the Database Image Copy utility (DFSUDMP0).
Advanced Image Copy Services process
The Advanced Image Copy Services process uses DFSMSdss or a utility with equivalent functions to reduce the time that IMS HP Image Copy accesses the database and minimizes unavailability of the database.
Three options are supported for the Advanced Image Copy Services process: COPY, FDUMP, and DUMP. The COPY and FDUMP options minimizes the time IMS HP Image Copy accesses the databases.
In COPY and FDUMP processes, the HASH check option, if requested, is done for the image copy data sets or the temporary data sets after the input database data sets are released.
| Option | Description |
|---|---|
| COPY | This option is the only method for creating image copies in Fast Recovery image copy format. Image copies in standard image copy format cannot be created. This option uses the FlashCopy® function or the SnapShot function of DFSMSdss to create clones of input database data sets. The clones become the output image copy data sets. This option requires more resources than other Advanced Image Copy Services options or the standard image copy process to maintain the image copy data sets. If you specify the DATA_MOVER=EMCSNAP option, Advanced Image Copy Services uses EMC TimeFinder instead of DFSMSdss to create a snapshot copy of the database. |
| FDUMP | Uses the FlashCopy function or the SnapShot function of DFSMSdss to create clones of input database data sets. After the input database data sets are released, the image copies are created in IMS image copy format or compressed image copy format from the clones. The output image copy data sets can be stored on a tape. This option requires the same amount of resources that are required by the COPY option while it creates the clones. However, because the clones are deleted at the end of the process, the resources required for maintaining the image copy data sets will be less than the resources required by the COPY option. If you specify the DATA_MOVER=EMCSNAP option, Advanced Image Copy Services uses EMC TimeFinder instead of DFSMSdss to create a snapshot copy of the database. |
| DUMP | This option is the only method for creating image copies of VSAM KSDS, that can be used for database recovery, with the concurrent image copy process. This option uses the DUMP function of DFSMSdss. When logical copies of the input data sets are created, the input database data sets are released. The output image copy data sets are committed when physical copies are created. However, if you request the stack option to create image copies on a stacked tape, a logical copy of the database data set does not start until a physical copy of the previous output data set is committed. The DUMP option converts the format of image copies from DFSMSdss format to IMS image copy format or compressed image copy format. Therefore, this option uses more CPU resources than the other two options of Advanced Image Copy Services. The performance is also slower than other two options. The DUMP option is not supported for the following types of database data sets:
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