IBM Performance Management

Managing the JVM heap size and DB2 bufferpool

Read and modify the JVM heap size and DB2® bufferpool size using the server_size.sh command.

Procedure

To read the recommended server size, run the following command from the /opt/ibm/ccm/ folder: server_size.sh. The output describes the number of CPUs, memory size, and free disk space in the server. Based on this output, a recommended server size is given, for example:
```
Number of CPUs: 2
Memory size: 8.00 GB
Free disk space: 65 GB
Recommended server size: extra_small
```

To change the server size and DB2 bufferpool, run the server_size.sh command again followed by the recommended size, for example, server_size.sh small. Note, this command stops and restarts the four Liberty servers. The JVM heap size is adjusted according to the values in the following table:

Table 1. JVM heap size setting
System size	Server1 application server	APMUI service	MIN (Liberty server instance)
Large	3072 MB	4096 MB	1024 MB
Medium	2048 MB	3072 MB	768 MB
Small	1536 MB	2048 MB	512 MB
Extra small	1560 MB	1560 MB	512 MB

The buffer pool is adjusted according to the values in the following table:

Table 2. DB2 Bufferpool
Database	Medium	Small	Extra small
DATAMART	200000	100000	50000
WAREHOUS	100000	75000	50000

Here is an example of the output:

# /opt/ibm/ccm/server_size.sh small
Setting 512MB heap size for service min.
Setting 1536MB heap size for service server1.
Setting 3072MB heap size for service apmui.
Setting ENABLE_MY_COMPONENTS to true for service apmui.
Setting WAREHOUS_IBMDEFAULTBP value to 75000.

   Database Connection Information

 Database server        = DB2/LINUXX8664 10.5.5
 SQL authorization ID   = DB2APM
 Local database alias   = WAREHOUS

DB20000I  The SQL command completed successfully.
Setting DATAMART_IBMDEFAULTBP value to 100000.

   Database Connection Information

 Database server        = DB2/LINUXX8664 10.5.5
 SQL authorization ID   = DB2APM
 Local database alias   = DATAMART

DB20000I  The SQL command completed successfully.
Stopping service apmui (PID 1155).
Service apmui is stopped.
Stopping service server1 (PID 29951).
Service server1 is stopped.
Stopping service min (PID 27920).
Service min is stopped.
Starting service min
.........
Service min is started (PID 17486).
Starting service server1
...................................................
Service server1 is started (PID 19100).
Starting service apmui
........................................................................
Service apmui is started (PID 22500).