namcd Settings

Make sure that the caching daemon, namcd, is running at all times.

Accessing eDirectory to get name service entries might cause a degradation in performance. namcd can persistently cache entries for workstations that are rebooted regularly. The persistent cache will improve access times, especially in setups with a large number of workstations.

You can enable or disable persistent caching to specify what information you want cached. If you enable persistent caching, all user profiles, group profiles, and the fully distinguished names (FDNs) of User objects will be cached. If persistent caching is disabled, only the User FDNs will be cached.

After configuring LUM, the uam cache daemon automatically retrieves all user and group entries from eDirectory and builds the cache because persistent caching is enabled by default. If you want to disable persistent caching, set the parameter enable-persistent-cache=No in the file /etc/nam.conf and restart the namcd daemon.

The settings for persistent caching, and the size of the cache for FDNs, user profiles and group profiles can be specified in the /etc/nam.conf file. Because the namcd daemon does not rescan the configuration file, you need to restart the namcd daemon after you make any modification to the configuration file.

Whenever the pam_nds and the nss_nds modules access eDirectory to get a User object, the namcd daemon updates the cache. namcd searches the cache before accessing eDirectory, thereby making the access quicker.

namcd Parameters

The following is a list of guidelines for the various namcd parameters.

• You can set the enable-persistent-cache parameter to enable or disable persistent caching, to specify what information you want cached.
• You can use the user-hash-size, and group-hash-size parameters to set the cache size for user FDNs, user profiles and group profiles respectively. The cache size should be a prime number greater than or equal to 1/4th of the users on that workstation.
• The persistent-cache-entries-aging-interval parameter can be set to specify the interval after which the user and group entries will be deleted from the persistent cache.
• The persistent-cache-refresh-period parameter can be set to specify how periodically user and group entries should be refreshed from the eDirectory database. Setting a large value will result in less network traffic and less load on the server, but the cache will reflect stale information if the eDirectory database is modified within that period.
• The persistent-cache-refresh-flag parameter can be set to specify whether all user and group entries or only those used in the current boot session are to be refreshed.
• Increase the value of the num-threads parameter according to the number of concurrent applications running.

The namcd parameters can be configured using the namconfig utility. Refer to Using namconfig for more details.