This read-only attribute specifies the number of file descriptors that Directory Server reserves for managing non-client connections, such as index management and managing replication. The number of file descriptors that the server reserves for this purpose subtracts from the total number of file descriptors available for servicing LDAP client connections.
Most installations of Directory Server should never need to change this attribute. However, consider increasing the value on this attribute if all of the following are true:
The server is replicating to a large number of consumer servers (more than 10), or the server is maintaining a large number of index files (more than 30).
The server is servicing a large number of LDAP connections.
You get error messages reporting that the server is unable to open file descriptors (the actual error message will differ depending on the operation that the server is attempting to perform), but these error messages are NOT related to managing client LDAP connections.
Increasing the value on this attribute may result in more LDAP clients being unable to access your directory. Therefore, when you increase the value on this attribute, increase the value on the nsslapd-maxdescriptors attribute also. Note that you may not be able to increase the nsslapd-maxdescriptors value if your server is already using the maximum number of file descriptors that your operating system allows a process to use. Refer to your operating system documentation for details. If this is the case, then reduce the load on your server by causing LDAP clients to search alternative directory replicas.
To assist you in computing the number of file descriptors you set for this attribute, use the following formula:
nsslapd-reservedescriptor = 20 + (NumBackends * 4) + NumGlobalIndexes + ReplicationDescriptors + ChainingBackendDescriptors + PTADescriptors + SSLDescriptors
The terms in the formula are as follows.
Number of LDBM databases.
Total number of configured indexes for all databases including system indexes. By default, there are 8 system indexes and 17 additional indexes per database.
NumSupplierReplicas + 8
Where NumSupplierReplicas is number of replicas in the server that can act as a supplier (hub or master).
NumChainingBackends * nsOperationConnectionsLimit
Where nsOperationConnectionsLimit is defined in the chained suffix configuration and 10 by default.
3 if PTA is configured, 0 if PTA is not configured.
5 (4 files + 1 listen socket) if SSL is configured, 0 if SSL is not configured.
1 to 65535
See attributes(5) for descriptions of the following attributes:
Obsolete: Scheduled for removal after this release