Parameter Tuning Guidelines

 

Table C-1 describes the result of increasing or decreasing various OpenVMS and BEA MessageQ parameters.

Table C-1 Parameter Tuning Guidelines

Action	Advantage	Disadvantage	Min/Max Value	Parameter Affected
Increase message buffer count	Allows higher number of pending messages.	MessageQ consumes more page file and global pages, and the page count increases for each process.	8-50,000 for each buffer pool	GBLPAGFIL GBLPAGES VIRTUALPAGECNT
Decrease message buffer count	Frees up page file for other programs.	Increases the probability of lost messages or poor performance due to resource exhaustion.	.	.
Increase message buffer reserve count	Allocates a higher number of message buffers for exclusive MessageQ internal use. Results in higher probability of unblocking and internal messages being delivered sucessfully.	Reduces the available number of message buffers for general use.	0 to all buffers in pool	.
Decrease message buffer reserve count	Increases available number of buffers.	Increases probability of lost messages or poor performance due to resource exhaustion.	.	.
Increase message buffer size	Allows transfer of larger blocks of data in a single call.	Consumes extra memory when data fills only a small portion of the buffer. Increases the size of each MessageQ process due to the creation of the local MessageQ buffers; two to four buffers depending on the features utilized.	1-31998 (small) 2-31999 (medium) 1500-65000 (large) S < M < L	PGFLQUO GBLPAGFIL GBLPAGES VIRTUALPAGECNT
Decrease message buffer size	Higher utilization of available memory.	Increases program complexity to disassemble and reassemble the data buffers when larger data transfers are required. Some features of MessageQ might not work because of the inability to allocate a large enough buffer.	.	.
Increase receive message quota	Allows a higher number of pending messages to build up during a burst condition.	A queue might consume a disproportionate amount of resources on its pending queue, causing other parts of the system to have problems.	0 bytes- 2 GB	.
Decrease receive message quota	Limits resource consumption of slow service rate queues or queues with no reader.	Queues might be unable to receive large messages. Messages might be lost or delayed because they cannot be queued.	.	.
Increase MRS NUM_DQF_AREAS	Allows more unconfirmed messages to be stored before a UMA is taken.	Uses more disk space and MRS Server resources.	100-1000000	.
Decrease MRS NUM_DQF_AREAS	Reduces disk and MRS Server resource consumption. Reduces time to locate a given message.	Reduces probability of storing a message.	.	.
Increase MRS CACHE_PERCENTAGE	Allows the queue to have more outstanding messages, which results in more overlap of the MRS Server I/O when applications process recoverable messages. This quota is a percentage of the byte or message receive quota.	Could cause the MRS Server to consume most or all of the receive byte/message quota on queue attachment.	1-100	.
Decrease MRS CACHE_PERCENTAGE	Reduces consumption of MessageQ buffers on queue attachment.	Lowers the amount of I/O overlap for reading messages out of the DQF and delivering the messages to the appropriate queue.	.	.
Increase MRS Maximum Queues	Allows the MRS Server to track more local and remote queues.	Causes the MRS Server to grow larger to contain these data structures.	128-2147483647	FILLM PGFLQUO VIRTUALPAGECNT
Decrease MRS Maximum Queues	Reduces the size of the MRS Server.	The MRS Server might be unable to track all the queues requested.	.	.
Increase MRS Maximum Messages	Allows the MRS Server to track more messages	Causes the MRS Server to grow larger to contain these data structures.	128-2147483647	PGFLQUO VIRTUALPAGECNT
Decrease MRS Maximum Messages	Reduces the size of the MRS Server.	The MRS Server might be unable to track all the messages requested.	.	.
Increase MRS NUM_SAF_AREAS	Allows the MRS Server to handle more remote queues.	Could increase the number of files and disk blocks used by the MRS Server.	0-1000000	.
Increase MRS NUM_SAF_AREAS	Limits the total number of remote queues that can have pending SAF messages.	Might be unable to track all queues requested.	.	.
Increas MRS AREA_SIZE	Reduces disk fragmentation and number of files needed to store messages.	Less efficient use of disk space.	128-16384 blocks for each file.	FILLM
Decrease MRS AREA_SIZE	More efficient use of disk space.	Could cause an inordinate number of disk files to be created. Causes disk and directory fragmentation.	.	.
Increase MRS Redelivery Timer	Less CPU overhead due to reduced retries.	Less responsive to changes in available resources.	0-5000	.
Decrease MRS Redelivery Timer	More responsive in systems with limited resources.	Could cause an inordinate amount of CPU attempting to retry message delivery.	.	.