Setting the Database Cache

A critical component of your directory server's overall performance is the size of the database (DB) cache. You need to determine your particular memory settings depending on your hardware, the number of entries in your directory, and your performance requirements. For example, when importing data by using the import-ldif utility, you must configure the directory server in such a way to minimize and avoid potential data cache eviction problems. Ideally, you should set the DB cache to a value that ensures that the whole database can fit into the cache. The size of the required heap depends on the number of entries and their size. For example, if you were importing 200K entries of 10Kbytes each, you might specify 2 Gbytes for the JVM heap size, then allocate at least 1 Gbyte for the directory server runtime environment and the rest for the DB cache.

To Set the Database Cache

You can set the DB cache by configuring the db-cache-percent or the db-cache-size properties with the dsconfig command-line utility. The db-cache-percent and the db-cache-size properties represent the maximum size that the server can use for the DB cache. If the database is smaller than the size set by either of these properties, only the size of the database is allocated to the JVM heap.

1. Change to the appropriate directory.

   (UNIX, Linux)  $ cd instance-dir/OUD/bin
   (Windows)      C:\> cd instance-dir\OUD\bat

2. Use the dsconfig command to set the db-cache-percent.

   This example sets the db-cache-percent to 50 percent. Thus, for a 2 Gbyte memory allocation, 1 Gbyte of memory will be allocated to the DB cache and the rest to the JVM.

   $ dsconfig -h localhost -port 4444 -D "cn=Directory Manager" -w password -X -n \
     set-backend-prop --backend-name userRoot --set db-cache-percent:50