Estimating concurrent I/O requests

The number of concurrent I/O requests is important when you calculate the number of data paths for your Db2 subsystem.

About this task

Db2 has a multi-tasking structure in which each user's request runs under a different task control block (TCB). In addition, the Db2 system itself has its own TCBs and SRBs for logging and database writes.

Procedure

To estimate the maximum number of concurrent I/O requests when your system is loaded with data:

Use the following formula:

MAX USERS + 600 prefetches + 600 asynchronous writes (A maximum of 300 deferred write engines and 300 castout engines asynchronous writes are supported)