Replication Server configuration parameters: init_sqm_write_delay and init_sqm_write_max_delay
In a low-volume system, set init_sqm_write_delay and init_sqm_write_max_delay to a low value so that the SQM Writer need not wait long before writing a partially full block. In a high-volume system, set these parameters higher because the SQM Writer rarely waits to fill a block.
Monitor how often the SQM Writer waits by reviewing counter 6038 – WritesTimerPop.
Determine the number of full or partially full blocks that have been written by reviewing these counters:
6002 – BlocksWriten
6041 – BlocksFullWrite
If counter 62006 – SleepsWriteQ is relatively high compared to counter 62002 – BlocksRead, SQM Readers must too often wait for the next block of messages to deliver downstream—which causes latency. Decrease the values of init_sqm_write_delay and init_sqm_write_max_delay so that SQM Writer does not wait to long before writing a partially full block.
Ideally, the ratio of counter 62004 – BlocksReadCached to counter 62002 – BlocksRead should be high, and counter 62006 – SleepsWriteQ should be relatively low. Such numbers would indicate that the SQM Writer is working approximately as fast as the SQM Reader, handing off blocks from the former to the latter without reading from disk. However, these are Replication Server–wide parameters, adjusting them to make one queue more efficient may decrease the efficiency of another.
