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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 |
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) |
PGFLQUO |
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- |
. |
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 |
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 |
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. |
. |
. |
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