Netscape NETSCAPE DIRECTORY SERVER 6.02, Руководство администратора

Страница: 425 / 568

Tuning Database Performance
Chapter 14 Tuning Directory Server Performance 425
• Changing the Database Checkpoint Interval
• Disabling Durable Transactions
• Specifying Transaction Batching
Optimizing Search Performance
You can improve server performance on searches by tuning database settings. The
database attributes that affect performance mainly define the amount of memory
available to the server.
To improve the cache hit ratio on search operations, you can increase the amount of
data that the Directory Server maintains in the database cache. Do this by
increasing the number of entries stored in the cache, and by increasing the cache
size. The maximum values that you can set for these attributes depends on the
amount of real memory on your machine. Roughly, the amount of available
memory on your machine should always be greater than:
(Maximum Entries in Cache + Maximum Cache Size) x average entry size
Use caution when changing these two attributes. Your ability to improve server
performance with these attributes depends on the size of your database, the
amount of physical memory available on your machine, and whether directory
searches are random (that is, if your directory clients are searching for random and
widely scattered directory data).
If your database does not fit into memory and if searches are random , attempting
to increase the values set on these attributes does not help directory performance.
In fact, changing these attributes may harm overall performance.
You can tune the following attributes:
• The attributes of the database that manages all other database instances. In
Directory Server Console, you can see only the databases that contain your
directory data, and the
NetscapeRoot
database. However, the server uses
another database to manage these. On this database, you can change the
following attributes to improve performance:
❍
The amount of memory that you want to make available for all databases
(maximum cache size attribute)
❍
The maximum number of entries you want the server to verify in response
to a search request (look-through limit attribute)