The database link plug-in attributes are also organized in an information tree, as shown in the following diagram:
All plug-in technology used by the database link instances is stored in the cn=chaining database plug-in node. This section presents the additional attribute information for the three nodes marked in bold in the cn=chaining database, cn=plugins, cn=config information tree in Figure 3.4, “Database Link Plug-in”.
This section covers global configuration attributes common to all instances are stored in the cn=config, cn=chaining database, cn=plugins, cn=config tree node.
This attribute lists the components using chaining. A component is any functional unit in the server. The value of this attribute overrides the value in the global configuration attribute. To disable chaining on a particular database instance, use the value None. This attribute also allows the components used to chain to be altered. By default, no components are allowed to chain, which explains why this attribute will probably not appear in a list of cn=config, cn=chaining database, cn=config attributes, as LDAP considers empty attributes to be non-existent.
| Parameter | Description |
|---|---|
| Entry DN | cn=config, cn=chaining database, cn=plugins, cn=config |
| Valid Values | Any valid component entry |
| Default Value | None |
| Syntax | DirectoryString |
| Example | nsActiveChainingComponents: cn=uid uniqueness, cn=plugins, cn=config |
This error detection, performance-related attribute specifies the 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. Once this delay period has been met, the database link tests the connection with the remote server.
| Parameter | Description |
|---|---|
| Entry DN | cn=config, cn=chaining database, cn=plugins, cn=config |
| Valid Values | Any valid delay period in seconds |
| Default Value | 60 seconds |
| Syntax | Integer |
| Example | nsMaxResponseDelay: 60 |
This error detection, performance-related attribute specifies the 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.
| Parameter | Description |
|---|---|
| Entry DN | cn=config, cn=chaining database, cn=plugins, cn=config |
| Valid Values | Any valid delay period in seconds |
| Default Value | 15 seconds |
| Syntax | Integer |
| Example | nsMaxTestResponseDelay: 15 |
This attribute, which can be both a global (and thus dynamic) configuration or an instance (that is, cn=database link instance, cn=chaining database, cn=plugins, cn=config) configuration attribute, allows the controls the database link forwards to be altered. The following controls are forwarded by default by the database link:
-
Managed DSA (OID: 2.16.840.1.113730.3.4.2)
-
Virtual list view (VLV) (OID: 2.16.840.1.113730.3.4.9)
-
Server side sorting (OID: 1.2.840.113556.1.4.473)
| Parameter | Description |
|---|---|
| Entry DN | cn=config, cn=chaining database, cn=plugins, cn=config |
| Valid Values | Any valid OID or the above listed controls forwarded by the database link |
| Default Value | None |
| Syntax | Integer |
| Example | nsTransmittedControls: 1.2.840.113556.1.4.473 |
Default instance configuration attributes for instances are housed in the cn=default instance config, cn=chaining database, cn=plugins, cn=config tree node.
This attribute shows the number of seconds that pass before the server checks for abandoned operations.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Range | 0 to maximum 32-bit integer (2147483647) seconds |
| Default Value | 1 |
| Syntax | Integer |
| Example | nsAbandonedSearchCheckInterval: 10 |
This attribute shows the maximum number of TCP connections the database link establishes with the remote server.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Range | 1 to 50 connections |
| Default Value | 3 |
| Syntax | Integer |
| Example | nsBindConnectionsLimit: 3 |
Contrary to what the name suggests, this attribute does not specify the number of times a database link retries to bind with the remote server but the number of times it tries to bind with the remote server. A value of 1 here indicates that the database link only attempts to bind once.
NOTE
Retries only occur for connection failures and not for other types of errors, scuh as invalid bind DNs or bad passwords.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Range | 0 to 5 |
| Default Value | 3 |
| Syntax | Integer |
| Example | nsBindRetryLimit: 3 |
This attribute shows the amount of time before the bind attempt times out. There is no real valid range for this attribute, except reasonable patience limits.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Range | 0 to 60 seconds |
| Default Value | 15 |
| Syntax | Integer |
| Example | nsBindTimeout: 15 |
Reserved for advanced use only. This attribute controls whether ACIs are evaluated on the database link as well as the remote data server. Changes to this attribute only take effect once the server has been restarted.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Values | on | off |
| Default Value | off |
| Syntax | DirectoryString |
| Example | nsCheckLocalACI: on |
This attribute shows the maximum number of concurrent bind operations per TCP connection.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Range | 1 to 25 binds |
| Default Value | 10 |
| Syntax | Integer |
| Example | nsConcurrentBindLimit: 10 |
This attribute specifies the maximum number of concurrent operations allowed.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Range | 1 to 50 operations |
| Default Value | 2 |
| Syntax | Integer |
| Example | nsConcurrentOperationsLimit: 5 |
This attribute specifies connection lifetime. Connections between the database link and the remote server can be kept open for an unspecified time or closed after a specific period of time. It is faster to keep the connections open, but it uses more resources. When the value is 0 and a list of failover servers is provided in the nsFarmServerURL attribute, the main server is never contacted after failover to the alternate server.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Range | 0 to limitless seconds (where 0 means forever) |
| Default Value | 0 |
| Syntax | Integer |
| Example | nsConnectionLife: 0 |
This attribute shows the maximum number of LDAP connections the database link establishes with the remote server.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Range | 1 to n connections |
| Default Value | 20 |
| Syntax | Integer |
| Example | nsOperationConnectionsLimit: 10 |
Reserved for advanced use only. This attribute can disable proxied authorization with a value of off.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Values | on | off |
| Default Value | on |
| Syntax | DirectoryString |
| Example | nsProxiedAuthorization: on |
This attribute controls whether referrals are returned by scoped searches. This attribute can be used to optimize the directory because returning referrals in response to scoped searches is more efficient. A referral is returned to all the configured farm servers.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Values | on | off |
| Default Value | off |
| Syntax | DirectoryString |
| Example | nsReferralOnScopedSearch: off |
This attribute specifies the default size limit for the database link in bytes.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Range | -1 (no limit) to maxmum 32-bit integer (2147483647) entries |
| Default Value | 2000 |
| Syntax | Integer |
| Example | nsslapd-sizelimit: 2000 |
This attribute specifies the default search time limit for the database link.
| Parameter | Description |
|---|---|
| Entry DN | cn=default instance config, cn=chaining database, cn=plugins, cn=config |
| Valid Range | -1 to maxmum 32-bit integer (2147483647) seconds |
| Default Value | 3600 |
| Syntax | Integer |
| Example | nsslapd-timelimit: 3600 |
This information node stores the attributes concerning the server containing the data. A farm server is a server which contains data on databases. This attribute can contain optional servers for failover, separated by spaces. For cascading chaining, this URL can point to another database link.
This attribute gives the LDAP URL of the remote server. A farm server is a server containing data in one or more databases. This attribute can contain optional servers for failover, separated by spaces. If using cascading changing, this URL can point to another database link.
| Parameter | Description |
|---|---|
| Entry DN | cn=database link instance name, cn=chaining database, cn=plugins, cn=config |
| Valid Values | Any valid remote server LDAP URL |
| Default Value | |
| Syntax | DirectoryString |
| Example | nsFarmServerURL: ldap://farm1.example.com:389 ldap://farm2.example.com:1389 |
This attribute gives the DN of the administrative entry used to communicate with the remote server. The multiplexor is the server that contains the database link and communicates with the farm server. This bind DN cannot be the Directory Manager, and, if this attribute is not specified, the database link binds as anonymous.
| Parameter | Description |
|---|---|
| Entry DN | cn=database link instance name, cn=chaining database, cn=plugins, cn=config |
| Valid Values | |
| Default Value | DN of the multiplexor |
| Syntax | DirectoryString |
| Example | nsMultiplexerBindDN: cn=proxy manager |
Password for the administrative user, given in plain text. If no password is provided, it means that users can bind as anonymous. The password is encrypted in the configuration file. The example below is what is shown, not what is typed.
| Parameter | Description |
|---|---|
| Entry DN | cn=database link instance name, cn=chaining database, cn=plugins, cn=config |
| Valid Values | Any valid password, which will then be encrypted using the DES reversible password encryption schema |
| Default Value | |
| Syntax | DirectoryString |
| Example | nsMultiplexerCredentials: {DES} 9Eko69APCJfF |
This attribute specifies the maximum number of times a database is allowed to chain; that is, the number of times a request can be forwarded from one database link to another.
| Parameter | Description |
|---|---|
| Entry DN | cn=database link instance name, cn=chaining database, cn=plugins, cn=config |
| Valid Range | 1 to an appropriate upper limit for the deployment |
| Default Value | 10 |
| Syntax | Integer |
| Example | nsHopLimit: 3 |
Attributes used for monitoring activity on the instances are stored in the cn=monitor, cn=database instance name, cn=chaining database, cn=plugins, cn=config information tree.
nsAddCount
This attribute gives the number of add operations received.
nsDeleteCount
This attribute gives the number of delete operations received.
nsModifyCount
This attribute gives the number of modify operations received.
nsRenameCount
This attribute gives the number of rename operations received.
nsSearchBaseCount
This attribute gives the number of base level searches received.
nsSearchOneLevelCount
This attribute gives the number of one-level searches received.
nsSearchSubtreeCount
This attribute gives the number of subtree searches received.
nsAbandonCount
This attribute gives the number of abandon operations received.
nsBindCount
This attribute gives the number of bind requests received.
nsUnbindCount
This attribute gives the number of unbinds received.
nsCompareCount
This attribute gives the number of compare operations received.
nsOperationConnectionCount
This attribute gives the number of open connections for normal operations.
nsBindConnectionCount
This attribute gives the number of open connections for bind operations.