DB2 tuning in WebSphere Commerce | Parameters related to transaction logs
DB2 Parameters related to memory
The database heap (DBHEAP) contains control block information for database objects (tables, indexes, and bufferpools), as well as the pool of memory from which the log buffer size (LOGBUFSZ) and catalog cache size (CATALOGCACHE_SZ) are allocated. Its setting is dependent on the number of objects in the database and the size of the two parameters mentioned.
In general, the following formula can be used to estimate the size of the database heap:
DBHEAP=LOGBUFSZ + CATALOGCACHE_SZ + (SUM(# PAGES in each bufferpool) * 3%)The log buffer is allocated from the database heap, and is used to buffer writes to the transaction logs for more efficient I/O. The default size of this setting one hundred and twenty-eight 4 K pages.
A recommended starting point for the log buffer size (LOGBUFSZ) in WebSphere Commerce implementations is 256.