Technical Blog Post
Abstract
db2fcmr and db2fcms are always one in purescale regardless of FCM_PARALLELISM
Body
The DPF and purescale are different architecture but both are using FCM(Fast Communication Manager) between partitions(or members) for communication.
Howver, different from DPF, db2fcmr and db2fcms in purescale are one regardless of FCM_PARALLELISM.
For this, the APAR IT24048 will be published in v111m4fp4, but this article was written for actual command results before v111m4fp4 and comparison with DPF.
1. db2fcm edus are one regardless of FCM_PARALLELISM in purescale - ref 1
2. db2fcm edus change by the FCM_PARALLELISM in DPF - ref 2
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ref 1 db2fcm edus are one regardless of FCM_PARALLELISM in purescale
(This test was done with v111m2fp2)
$ db2stop
01/30/2018 22:01:21 1 0 SQL1064N DB2STOP processing was successful.
01/30/2018 22:01:21 0 0 SQL1064N DB2STOP processing was successful.
01/30/2018 22:01:22 2 0 SQL1064N DB2STOP processing was successful.
SQL1064N DB2STOP processing was successful.
$ db2 update dbm cfg using FCM_PARALLELISM 4
DB20000I The UPDATE DATABASE MANAGER CONFIGURATION command completed
successfully.
$ db2 get dbm cfg | grep -i fcm
Number of FCM buffers (FCM_NUM_BUFFERS) = AUTOMATIC(4096)
FCM buffer size (FCM_BUFFER_SIZE) = 32768
Number of FCM channels (FCM_NUM_CHANNELS) = AUTOMATIC(2048)
FCM parallelism (FCM_PARALLELISM) = 4
$ db2start
01/30/2018 22:02:11 1 0 SQL1063N DB2START processing was successful.
01/30/2018 22:02:11 2 0 SQL1063N DB2START processing was successful.
01/30/2018 22:02:12 0 0 SQL1063N DB2START processing was successful.
SQL1063N DB2START processing was successful.
$ db2pd -edus | grep -i db2fcm
2571 2571 5440409 db2fcmr 0 0.001410 0.000366
2057 2057 97976531 db2fcms 0 0.001400 0.000264
>>>>> nubmer of db2fcms and db2fcmr are not increased based on the fcm_parallelism cfg parameter.
-------------------------------------
ref 2 db2fcm edus change by the FCM_PARALLELISM in DPF
$ db2start
01/31/2018 18:32:44 1 0 SQL1063N DB2START processing was successful.
01/31/2018 18:32:45 0 0 SQL1063N DB2START processing was successful.
01/31/2018 18:32:48 2 0 SQL1063N DB2START processing was successful.
SQL1063N DB2START processing was successful.
$ db2 get dbm cfg | grep -i fcm
Number of FCM buffers (FCM_NUM_BUFFERS) = AUTOMATIC(4096)
FCM buffer size (FCM_BUFFER_SIZE) = 32768
Number of FCM channels (FCM_NUM_CHANNELS) = AUTOMATIC(2048)
FCM parallelism (FCM_PARALLELISM) = AUTOMATIC(8)
$ db2stop
01/31/2018 18:33:53 1 0 SQL1064N DB2STOP processing was successful.
01/31/2018 18:33:53 0 0 SQL1064N DB2STOP processing was successful.
01/31/2018 18:33:55 2 0 SQL1064N DB2STOP processing was successful.
SQL1064N DB2STOP processing was successful.
$ db2 update dbm cfg using FCM_PARALLELISM 4
DB20000I The UPDATE DATABASE MANAGER CONFIGURATION command completed
successfully.
$ db2 get dbm cfg | grep -i fcm
Number of FCM buffers (FCM_NUM_BUFFERS) = AUTOMATIC(4096)
FCM buffer size (FCM_BUFFER_SIZE) = 32768
Number of FCM channels (FCM_NUM_CHANNELS) = AUTOMATIC(2048)
FCM parallelism (FCM_PARALLELISM) = 4
$ db2start
01/31/2018 18:34:17 1 0 SQL1063N DB2START processing was successful.
01/31/2018 18:34:18 0 0 SQL1063N DB2START processing was successful.
01/31/2018 18:34:18 2 0 SQL1063N DB2START processing was successful.
SQL1063N DB2START processing was successful.
$ db2pd -edus | grep -i db2fcm
5141 5141 103613371 db2fcmr 0 0.001167 0.000114
4627 4627 67109487 db2fcmr 0 0.001132 0.000118
4113 4113 119341729 db2fcmr 0 0.001218 0.000138
3599 3599 129893029 db2fcmr 0 0.001389 0.000292
3085 3085 81199953 db2fcms 0 0.001332 0.000327
2571 2571 10814439 db2fcms 0 0.001408 0.000281
2057 2057 113508359 db2fcms 0 0.001443 0.000280
1543 1543 69206293 db2fcms 0 0.001476 0.000325
-------------------------------------
For FCM_PARALLELISM, please check the following link.
fcm_parallelism - Internode communication parallelism configuration parameter
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UID
ibm13286041