Mirroring Under Novell Netware

This page provides information about:

Enabling Mirroring

To install the CMDGODI.LAN driver software, follow the normal network adapter driver installation procedure. (See Installing the CMDGODI.LAN Driver on Novell Netware Systems)

The slot, IO Port or burned-in address (BIA) of both the master and slave adapters must be known in order to install mirroring. If you do not know these values, type LOAD CMDGODI DISPLAY at the server command prompt to display details of all supported adapters in the machine.

To enable mirroring with CMDGODI, the location of a slave adapter must be given when the master adapter is loaded. As with the master adapter, the slave adapter can be selected by either its IO Port, Slot or BIA using the command line parameters MIRRORPORT=<n>, MIRRORSLOT=<n> or MIRRORBIA=<n> respectively. Also, you must specify a locally administered node address (LAA) using the NODE=<n> parameter.

For example, the following line (which can be entered at the server command prompt or in autoexec.ncf) loads CMDGODI onto a master adapter located in Slot 2 and associates a slave adapter at Slot 3 with the master:

LOAD CMDGODI SLOT=2 MIRRORSLOT=3 NODE=400000000001

If the driver loads successfully, a console message gives details of the master and slave adapters.

Advanced Mirroring Configuration

Once mirroring has been installed, the driver will initiate a mirror switch if the adapter closes or fails in some detectable way. Additionally, mirroring can be configured to cause a mirror switch in the following circumstances:

These timeout values are set by adding the following parameters to the LOAD CMDGODI ... command line:

This parameter can be used to force a mirror switch after the adapter has been transmitting beacon frames for the number of seconds given by the timeout value. In the event of a lobe cable fault, the adapter will beacon before eventually closing - the adapter will not close until several seconds after the cable fault. By setting the BEACON timeout to a small value, a mirror switch will occur before adapter actually closes, therefore reducing the time before the server regains its network connection.

This parameter can be used to force a mirror switch after the adapter has been signalling a lobe cable fault for the number of seconds given by the timeout value. This parameter can be used to cause a mirror switch to occur before the adapter actually closes due to a lobe cable fault and is therefore similar in function to the BEACON parameter.

If the hub to which the master adapter is connected loses power or the hub port is accidentally disabled, the hub port may wrap causing the adapter to become a single station without the adapter actually closing. To cause the driver to initiate a mirror switch in this case, the SINGLE timeout value must be set. The timeout value is the number of seconds to wait while in single station mode before a switch is initiated

These parameters are not active unless you configure them. For example, a mirror switch will not take place if the adapter has been transmitting beacon frames unless you set a value for the BEACON=<timeout> parameter.

Testing Mirroring

After installing mirroring, it is advisable to test that mirroring is operating properly. Attach some machines to the server to generate some network traffic (copy some files, perhaps) then remove the lobe cable from the master adapter. The slave adapter should open after a few seconds and the client machines should remain connected to the server.

Diagnostic Information

All driver diagnostic information is displayed on the server console.

If mirroring has been badly configured, the driver may fail to load in which case a diagnostic message will displayed.

When a mirror switch occurs, a message which includes the reason for the switch is displayed.

The custom statistic "Mirror switch count" records the number of times a mirror switch has occurred. Driver statistics are viewed using MONITOR.NLM.

See Also: