The TCMF multi-target mainframe system function provides compatibility with the Multiple Target PPRC function that is supported by IBM® DS series storage. When the TCMF multi-target function is enabled on the storage system, a 3DC configuration with three TrueCopy for Mainframe (TCz) sites can be created. In the 3DC multi-target configuration, the primary volume data is copied to two secondary volumes.
You can enable and disable the mainframe system functions by using Command Control Interface (CCI) (raidcom modify mainframe_system_function).
If the storage system restarts with volatilization (forced outage with volatile DKC and media chassis, PS-OFF to volatile PS-ON, or offline microcode replacement), the TCMF multi-target setting is disabled. Make sure to re-enable this setting after the volatilization.
Precautions when using the TCMF multi-target setting
Be aware of the following precautions when the TCMF multi-target function is enabled:
- In a storage system with TCMF multi-target enabled, volumes with CU numbers from 0x80 to 0xfe cannot be used for TC/TCz primary or secondary volumes. However, in a storage system that does not support the PPRC multi-target function, volumes with any CU numbers can be used for TC/TCz volumes regardless of whether TCMF multi-target is enabled or disabled.
- You cannot build a PPRC multi-target configuration if the volume, in which 0x8000 is added to the LDEV ID of the volume used in the PPRC multi-target configuration, is set as a command device or remote command device. For example, if a volume with LDEV ID 0x8010 is set as a command device or remote command device, you cannot build a PPRC multi-target configuration using a volume with LDEV ID 0x0010.
- A TCz pair created by storage systems with TCMF multi-target enabled is a pair that supports PPRC multi-target, even if it is a one-to-one pair.
The copy operation during an incremental resync operation is either a full data copy or a differential data copy. The copy operation depends on whether a pair supports the differential data copy function in the PPRC multi-target configuration. For more information about the copy operation during the incremental resync operation and how to switch the copy operation from the full data copy to the differential data copy, see .
- In a PPRC multi-target configuration, you can create up to two secondary sites for a primary site. You cannot add a third secondary site.
- Use the same fence level between the two TCz pairs in a PPRC multi-target configuration.
- If the volume of the consistency group function that spans multiple storage systems operated from CCI coexists with the volume of PPRC multi-target, group suspend (Freeze) from CCI might fail and result in failure suspend.
- The PPRC multi-target function cannot be used on z/VM®.
- A volume defined with subchannel set #1, 2, or 3 (not #0) cannot be used as a secondary volume for the PPRC multi-target function.
- A PAV alias device defined with subchannel set #1, 2, or 3 (not #0) can be used as a volume for the PPRC multi-target function.