Red Hat 8.1, Command Reference Manual

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cn=config
43
Parameter Description
Default Value 2097152
Syntax Integer
Example nsslapd-maxbersize: 2097152
2.3.1.77. nsslapd-maxdescriptors (Maximum File Descriptors)
This attribute sets the maximum, platform-dependent number of file descriptors that the Directory
Server tries to use. A file descriptor is used whenever a client connects to the server and also for
some server activities, such as index maintenance. File descriptors are also used by access logs,
error logs, audit logs, database files (indexes and transaction logs), and as sockets for outgoing
connections to other servers for replication and chaining.
The number of descriptors available for TCP/IP to serve client connections is determined by
nsslapd-conntablesize
, and is equal to the
nsslapd-maxdescriptors
attribute minus the
number of file descriptors used by the server as specified in the
nsslapd-reservedescriptors
attribute for non-client connections, such as index management and managing replication. The
nsslapd-reservedescriptors
attribute is the number of file descriptors available for other uses
as described above. See
Section 2.3.1.89, “nsslapd-reservedescriptors (Reserved File Descriptors)”
.
The number given here should not be greater than the total number of file descriptors that the
operating system allows the
ns-slapd
process to use. This number differs depending on the
operating system.
If this value is set too high, the Directory Server queries the operating system for the maximum
allowable value, and then use that value. It also issues a warning in the error log. If this value is set to
an invalid value remotely, by using the Directory Server Console or
ldapmodify
, the server rejects
the new value, keep the old value, and respond with an error.
Some operating systems let users configure the number of file descriptors available to a process.
See the operating system documentation for details on file descriptor limits and configuration. The
dsktune
program (explained in the
Directory Server Installation Guide
) can be used to suggest
changes to the system kernel or TCP/IP tuning attributes, including increasing the number of file
descriptors if necessary. Increased the value on this attribute if the Directory Server is refusing
connections because it is out of file descriptors. When this occurs, the following message is written to
the Directory Server's error log file:
Not listening for new connections -- too many fds open
See
Section 2.3.1.38, “nsslapd-conntablesize”
for more information about increasing the number of
incoming connections.
NOTE
UNIX shells usually have configurable limits on the number of file descriptors. See the
operating system documentation for further information about
limit
and
ulimit
, as
these limits can often cause problems.
The server has to be restarted for changes to this attribute to go into effect.