HP-UX Directory Server 8.1 administrator guide
The first attribute, nsMaxResponseDelay, sets a maximum duration for an LDAP operation
to complete. If the operation takes more than the amount of time specified in this attribute, the
database link's server suspects that the remote server is no longer online.
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 2-6 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
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.
nsMaxResponseDelay
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 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.
nsMaxTestResponseDelay
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.
78 Configuring directory databases