Communication Methods › Virtual Control File Sizing Considerations

Virtual Control File Sizing Considerations

The VCF size is a mirror image of the primary backup DASD control file when the CA MIM complex executes in a mixed CTC and DASD environment.

The VCF image contains the same number of blocks (of size MIMINIT BLKSIZE), as the primary backup DASD control file. The primary backup DASD control file is defined as the DASD control file that was in use when the migration to the VCF took place. CA MIM supports up to 100 DASD control files. We recommend that alternate DASD control files be progressively larger in size than the primary control file. When the primary DASD control file or the VCF becomes full, a migration to a larger alternate DASD control file is successful. The larger alternate DASD control file yields an equally larger size VCF when compared to the original DASD control file size.

When running in a VCF-only environment ( MIMINIT COMMUNICATION=CTCONLY), the VCF image size is dynamic.

VCF sizing:

• Determine the initial VCF size by multiplying the MIMINIT BLKSIZE specification by the MIMINIT VCFMAXBLOCKS specification.
• When the VCF image size needs increased, the detecting system expands the VCF dynamically.
• As each external system accesses the VCF, the system detects that the VCF has been expanded and begins operating with the increased file size.
• Depending upon the MIMINIT BLKSIZE specification, the VCF image can expand to a maximum of 2 GB.