HP-UX Directory Server Administrator Guide HP-UX Directory Server Version 8.1 (5900-3098, May 2013)

After the nsMaxResponseDelay period has been met, the database link pings the remote server.
During the ping, the database link issues another LDAP request, a simple search request for an
object that does not exist in the remote server. The duration of the ping is set using the
nsMaxTestResponseDelay.
If the remote server does not respond before the nsMaxTestResponseDelay period has passed,
then an error is returned, and the connection is flagged as down. All connections between the
database link and remote server will be blocked for 30 seconds, protecting the server from a
performance degradation. After 30 seconds, operation requests made by the database link to the
remote server continue as normal.
Both attributes are stored in the cn=config,cn=chaining
database,cn=plugins,cn=config entry. The following table describes the attributes in more
detail:
Table 7 Database link processing error detection parameters
DescriptionAttribute name
Maximum amount of time it can take a remote server to respond to an LDAP
operation request made by a database link before an error is suspected. This
nsMaxResponseDelay
period is given in seconds. The default delay period is 60 seconds. After this
delay period has been met, the database link tests the connection with the
remote server.
Duration of the test issued by the database link to check whether the remote
server is responding. If a response from the remote server is not returned before
nsMaxTestResponseDelay
this period has passed, the database link assumes the remote server is down,
and the connection is not used for subsequent operations. This period is given
in seconds. The default test response delay period is 15 seconds.
2.4.7.3 Managing threaded operations
Generally, Directory Server performs best using a limited number of threads for processing
operations. A limited number of threads can generally process operations very quickly, preventing
the queue of operations waiting for a free thread from growing too long.
However, the database link forwards operations to remote servers for processing. The database
link contacts the remote server, forwards the operation, waits for the result, then sends the result
back to the client application. The entire operation can take much longer than a local operation.
While the database link waits for results from the remote server, it can process additional operations.
By default, the number of threads used by the server is 30. However, when using database links,
performance can be improved by increasing the number of threads available for processing
operations. While the local CPU waits for a response from a remote server, it can process other
operations rather than stand idle.
To change the number of threads used for processing operations, change the
nsslapd-threadnumber global configuration attribute in the cn=config entry. Increasing the
thread number can improve performance; the default thread number is 30. Restart the server after
changing the thread count to apply the changes.
2.4.8 Configuring cascading chaining
The database link can be configured to point to another database link, creating a cascading
chaining operation. A cascading chain occurs any time more than one hop is required to access
all the data in a directory tree.
• “Overview of cascading chaining” (page 77)
• “Configuring cascading chaining using the console” (page 78)
• “Configuring cascading chaining from the command line” (page 80)
• “Detecting loops” (page 81)
76 Configuring Directory Databases