Performance Tuning for Content Manager

158 Performance Tuning for Content Manager

For example, after you issue the db2start command for the first time, you should

receive output similar to the following messages in your db2diag.log file:

ADM0506I DB2 has automatically updated the "semmni" kernel

parameter from "128" to the recommended value "1024".

2004-07-31-16.38.59.074791 Instance:db2inst1

Node:000

PID:15996(db2sysc) TID:8192 Appid:none

base sys utilities sqlesysc_main Probe:9

ADM0506I DB2 has automatically updated the "msgmni" kernel

parameter from "16" to the recommended value "1024".

2004-07-31-16.38.59.076916 Instance:db2inst1

Node:000

PID:15996(db2sysc) TID:8192 Appid:none

base sys utilities sqlesysc_main Probe:9

ADM0506I DB2 has automatically updated the "shmmax" kernel

parameter from "33554432" to the recommended value "268435456".

2004-07-31-16.39.01.262594 Instance:db2inst1

Node:000

PID:15994(db2star2) TID:8192 Appid:none

base sys utilities startdbm Probe:911

ADM7513W Database manager has started.

7.3.3 Configure semaphores settings

Linux default kernel tuning for semaphores is not meant for enterprise

applications such as DB2. On RHEL3 for example, it is:

# more /proc/sys/kernel/sem

250 32000 32 1024

Using the default values might cause the application to run out of semaphores.

To increase semaphore settings, use the following command:

echo 500 512000 64 2048 > /proc/sys/kernel/sem

The parameters are, in order:

SEMMSL Semaphores per ID

SEMMNS (SEMMNI*SEMMSL) Max semaphores in system

SEMOPM Max operations per semaphore call

SEMMNI Max semaphore identifiers

7.3.4 Configure message queues

Message queues are used by the Linux operating system and by databases to

facilitate communications among processes. Databases might run out of