Agent Technology › Performance Considerations › Determine the Best Values for the Three Caches

Determine the Best Values for the Three Caches

To minimize I/O EXCPs to the object store database, you must set the cache size parameters to the total size of all of the files within each of the different table categories (with the exception of the rollback files, which are suffixed with MMA, RBI, MM2, and RB2). The following are the calculations you should perform to determine the size for each of the cache parms:

-x

Sum the size of the following files (divide the result by 1024 to convert to KB):

• OBJECTS.CHK
• OBJECTS.FBM
• OBJECTS.MDI
• OBJECTS.MDS
• Sum of OBJECTS file sizes in bytes / 1024

-y

Sum the size of the following files (Divide the result by 1024 to convert to KB):

• PROPVH.CHK
• PROPVH.FBM
• PROPVH.MDI
• PROPVH.MDS
• Sum of PROPVH file sizes in bytes / 1024

-z

Sum the size of the following files (Divide the result by 1024 to convert to KB):

• VOTREE.CH2
• VOTREE.CM2
• Sum of VOTREE file sizes in bytes / 1024

Note: These calculations should be performed only after all MIBs have been loaded and all agent instances have been started. You must ensure that your Agent Technology for z/OS Services have been shut down before you attempt to modify the awservices.cfg file (otherwise your changes will not be preserved).

Even if only one agent is active at a time but the store contains all MIBs, the size of the cache for the VOTREE table needs to be at least the same as the size of its corresponding file. A smaller value (even within a few KB) leads directly to an increase of EXCPs.

This is not the case for the two other tables, although the best size for the corresponding caches needs to be higher than the size really occupied by the corresponding MIB definition, plus the size used by all the instances of the agent. Therefore, we recommend you allocate them as the total size of the different tables.