Effects of Using Autodetect Setting on Cluster NIC

• Microsoft Windows NT Server, Enterprise Edition version 4.0 - Microsoft Cluster Server

SYMPTOMS

If you use a multiple speed Ethernet network adapter for cluster communications and configure the adapter to "autosense" the network speed, the adapter may cause problems within the cluster.

CAUSE

The "autosense" mode of some 10/100 Ethernet adapters may automatically detect the speed of the connected network. However, during the detection process, packets cannot be handled by the adapter and must be queued. Some adapters may inadvertently trigger the autodetection process to reoccur intermittently. As a result, communications are queued and communication delayed. Delays of this nature may cause cluster nodes not to receive critical packets in a timely fashion and may cause premature failover of cluster resources.

RESOLUTION

For best results, configure the adapter manually for the network speed to avoid the potential performance impact and possible unnecessary failovers in the cluster.