Enabling and Disabling Specific-Purpose Coservers

When the database server starts after you add coservers of any kind, all newly defined coservers are enabled by default. Fully capable coservers are always enabled; you cannot disable or enable a fully capable coserver.

You can enable specific-purpose coservers either permanently or temporarily during peak workload periods. During normal processing periods, you might disable specific-purpose coservers and return the nodes that host them to their usual use (for example, as hot-standby nodes or for processes not associated with the database server).

After you disable a specific-purpose coserver, use the onutil ENABLE COSERVER coserver_name command when the database server is in quiescent mode to enable the coserver.

Enabling a Specific-Purpose Coserver or Coserver Capability:

|--ENABLE--+----------+--+----+--COSERVER--_--coserver_number---|
           +-COMPUTE--+  '-ON-'
           '-TEMPDATA-'

For example, if you configured coserver 4 with both COMPUTE and TEMPDATA capabilities and you used the onutil command to disable the coserver, use the following command to enable it:

onutil ENABLE COSERVER 4;

You do not need to specify capabilities when you are enabling a previously disabled coserver.

To enable a previously disabled capability on a coserver, use the onutil ENABLE capability_name ON COSERVER coserver_name command when the database server is in quiescent mode. For example, for coserver 4 if you disabled COMPUTE capability, enter the following command:

onutil ENABLE compute ON COSERVER4;

For more information about the onmode and oninit commands, see the utilities chapter in the IBM Informix: Administrator's Reference.

Use the onutil DISABLE COSERVER coserver_number command while the database server is in quiescent mode to disable a specific-purpose coserver completely so that you can use the node for other purposes.

Deleting a Specific-Purpose Coserver ::

|--DISABLE--+----------+--COSERVER--coserver_number-------------|
            +-COMPUTE--+
            '-TEMPDATA-'

For example, if you configured coserver4 as a specific-purpose coserver, enter the following command to disable it:

onutil DISABLE COSERVER 4;

To disable one of the capabilities of the coserver, use the onutil DISABLE capability_name COSERVER coserver_number command while the database server is in quiescent mode. For example, if you have configured coserver4 with both COMPUTE and TEMPDATA capability, to disable only the COMPUTE capability, enter the following command:

onutil DISABLE COMPUTE COSERVER 4;

Even if you disable all capabilities of a coserver, the coserver is still brought online. The coserver node is not available for other uses.

If you disable a coserver or coserver capability, the coserver or capability is disabled until you explicitly enable it.

In addition to enabling and disabling a specific-purpose coserver, you can enable or disable only its capabilities. This ability is particularly useful if you configured specific-purpose coservers with both the COMPUTE and TEMPDATA options to the CAPABILITY configuration parameter.

You can disable and enable all of the capabilities with which a specific-purpose coserver has been configured; however, you cannot add a capability. Even if all the capabilities of a specific-purpose coserver are disabled, the coserver is still brought online when you bring the database server back online. Disabled capabilities remain disabled until they are explicitly enabled.

Message-Log Messages

Four new messages that correspond to enable coserver, disable coserver, add coserver, and delete coserver operations are written to the message log. A new warning message is also written to the message log when you delete a coserver to indicate that the number of coservers in the configuration is inconsistent.

The following examples show the messages that the database server writes to the message log:

Disabled all capability on Coserver 3.
Disabled COMPUTE capability on Coserver 3.
Enabled COMPUTE capability on Coserver 3.
Coserver 3 deleted.
Coserver 3 added.

The following errors might appear:

-23561 CM error: Cant delete a Coserver ID that is not the 
                 highest ID.
-23562 CM error: Cant delete a Coserver ID that exists in the 
                 \$ONCONFIG file.
-23563 CM error: Cant enable a capability on a coserver 
                 configured as fully capable
-23564 CM error: Cant disable a capability on a coserver 
                 configured as fully capable
-23565 CM error: Capability is not configured on coserver.
-23566 CM error: Coserver counts are inconsistent, only the delete 
                 coserver command is allowed.
-23567 CM error: Dynamic Coserver Management is not currently 
                 supported.
-23568 CM error: Deleting fully capable coserver is not supported.
-23569 CM error: Permanent dbspaces are not supported on a target 
                 coserver.
-23570 CM error: XTM must start in idle state to allow removing 
                 coservers from the system.
-23571 CM error: Coserver 1 must be a fully capable coserver.
-23572 CM error: The Capabilities for coserver %d have changed.
-23573 CM error: The coserver type specified is invalid.
80635 The coserver does not have the capability to host the data.
32843 onmode: not enough coservers are configured to leave 
                 quiescent mode.