Symantec 5 Setting the kernel.panic tunable, Optimizing LLT media speed settings on private NICs

48Preparing to install VCS Performing preinstallation tasks

Setting the kernel.panic tunable

By default, the kernel.panic tunable is set to zero. Therefore the kernel does not reboot automatically if a node panics. To ensure that the node reboots automatically after it panics, this tunable must be set to a non zero value.

To set the kernel.panic tunable

1Set the kernel.panic tunable to a desired value in the /etc/sysctl.conf file.

For example, kernel.panic = 10, will assign a value 10 seconds to the kernel.panic tunable. This step makes the change persistent across reboots.

2Run the command:

sysctl -w kernel.panic=10

In case of a panic, the node will reboot after 10 seconds.

Optimizing LLT media speed settings on private NICs

For optimal LLT communication among the cluster nodes, the interface cards on each node must use the same media speed settings. Also, the settings for the switches or the hubs that are used for the LLT interconnections must match that of the interface cards. Incorrect settings can cause poor network performance or even network failure.

Guidelines for setting the media speed of the LLT interconnects

Review the following guidelines for setting the media speed of the LLT interconnects:

■Symantec recommends that you manually set the same media speed setting on each Ethernet card on each node.

■If you have hubs or switches for LLT interconnects, then set the hub or switch port to the same setting as used on the cards on each node.

■If you use directly connected Ethernet links (using crossover cables), set the media speed to the highest value common to both cards, typically 100_Full_Duplex.

■Symantec does not recommend using dissimilar network cards for private links.

Details for setting the media speeds for specific devices are outside of the scope of this manual. Consult the device’s documentation for more information.