Red Hat DIRECTORY SERVER 8.0, Administration Manual, Page: 423 / 552

Tuning Transaction Logging
405
To configure the default database attributes that apply to all other database instances:
1. In the Directory Server Console, select the
Configuration
tab; then, in the navigation tree, expand
the Data Icon, and highlight the Database Settings node.
This displays the Database tabs in the right pane.
1. Select the
LDBM Plug-in Settings
tab in the right pane.
This tab contains the database attributes for all databases stored on this server.
2. In the
Maximum Cache Size
field, enter a value corresponding to the amount of memory to
make available for all databases. This values is for the total of the
entire backend
, meaning all
databases cumulatively, the amount per single database instance.
3. In the
Look-Through Limit
field, enter the maximum number of entries for the server to check in
response to a search request.
4. There are two ways to set the amount of memory in bytes to make available for import. The default
is to have auto cache sizing, meaning 50% of the free memory is allocated for the import cache.
It is also possible to set the import cache size manually by deselecting the
Use Cache Auto-Size
checkbox and then setting the value in the
Import Cache Size
field. For creating a very large
database from LDIF, set this attribute as large as possible, depending on the memory available on
the machine. The larger this parameter, the faster the database is created.
WARNING
Setting this value too high can cause import failures because of a lack of memory.
To configure the attributes of each database that stores the directory data:
1. In the Directory Server Console, select the
Configuration
tab; then, in the navigation tree, expand
the Data Icon. Expand the suffix of the database to tune, and highlight the database.
The tabs displayed in the right pane control parameter settings for this database.
1. Select the
Database Settings
tab in the right pane.
2. Enter the amount of memory to make available for cached entries in the
Memory Available for
Cache
field.
15.2.2. Tuning Transaction Logging
Every Directory Server contains a transaction log which writes operations for all the databases it
manages. Whenever a directory database operation such as a modify is performed, the server
logs the operation to the transaction log. For best performance, the directory does not perform the
operation immediately. Instead, the operation is stored in a temporary memory cache on the Directory
Server until the operation is completed.
If the server experiences a failure, such as a power outage, and shuts down abnormally, the
information about recent directory changes that were stored in the cache is lost. However, when
the server restarts, the directory automatically detects the error condition and uses the database
transaction log to recover the database.