VSP One Block 85 is compatible with the IBM® zHyperWrite function. The zHyperWrite function enables hosts to write DB2® logs directly to the TCz P-VOL and the TCz S-VOL. To use the zHyperWrite function on the storage system, the following are required:
- PTF
- z/OS® V2R1 or later
- The Basic HyperSwap® function of TPC-R/CSM, or the HyperSwap® function of GDPS
For details, see the IBM® documentation.
- The zHyperWrite function cannot be used in a 3DC delta resync configuration with URz. I/Os reject commands when you use the zHyperWrite function in the 3DC delta resync configuration with URz (F/M=0F, Reason Code=78).
- The zHyperWrite function and the Preserve Mirror FlashCopy® function can
be used together. The following restrictions apply when using the
zHyperWrite function with the Preserve Mirror FlashCopy® function.
- If the Preserve Mirror FlashCopy® function is used to back up the
log volume being updated with zHyperWrite, there might be a
difference in the backup data between the two Compatible FlashCopy® target
volumes. This is expected behavior as an IBM® zHyperWrite program.
If there is a difference in the backup data between the target volumes, the storage system data can be recovered by reaquiring the backup data using the Preserve Mirror FlashCopy® function when there is no update by zHyperWrite.
- If a Compatible FlashCopy® relationship is established, the writing with zHyperWrite to the target TCz overwrites the Compatible FlashCopy® data. In addition, if the Compatible FlashCopy® relationship is established while the writing with zHyperWrite is in progress, the zHyperWrite data is overwritten by the copy operation with Compatible FlashCopy®.
- If the Preserve Mirror FlashCopy® function is used to back up the
log volume being updated with zHyperWrite, there might be a
difference in the backup data between the two Compatible FlashCopy® target
volumes. This is expected behavior as an IBM® zHyperWrite program.
- If CFW data is set to Primary Volume Only of VSP One Block Administrator, the zHyperWrite function cannot be used. In this case, to use the function, delete TCz pairs, disable the function switch #12, and then re-create the pairs.
- If you use the zHyperWrite function for created TCz pairs, delete them first, disable the function switch #12, and then re-create the pairs.
To use the zHyperWrite function in a 3DC multi-target configuration with URz, make sure to enable the zHyperWrite + 3DC multi target mainframe system function (raidcom modify mainframe_system_function). However, the zHyperWrite function cannot be used if the storage system model does not support the zHyperWrite function or if the supported and unsupported microcode versions are contained in the 3DC multi-target configuration.
To enable the zHyperWrite function, you must set system option mode (SOM) 1091 to ON on both the MCU and the RCU. When SOM 1091 is set to ON on the MCU and RCU, the host recognizes that the storage systems at the primary and secondary sites support the function, and then the function is enabled. To disable the zHyperWrite function, set SOM 1091 to OFF on the MCU. (When the SOM is OFF on the MCU, the function is invalidated at both sites.)
In some cases, the zHyperWrite function is not enabled (or disabled) after SOM 1091 is set to ON (or OFF). After SOM 1091 is set to ON (or OFF), verify that the zHyperWrite function is enabled (or disabled) by using RMF to see if the host is writing DB2® logs directly to the S-VOL of a TCz pair in which the DB2®log dataset is stored. If the host is writing DB2® logs directly to the S-VOL, the zHyperWrite function is enabled.
When SOM 1091 is set to ON (or OFF) but the zHyperWrite function is not enabled (or disabled), perform the following procedure to enable (or disable) the function.
The setting of CFW data for PPRC/TCz pairs must be set to Secondary Volume Copy. CFW data is copied to the S-VOL. If this is not set, zHyperWrite will not function.