Configuring a low-priority link

Low-priority link (LLT) can be configured to use a low-priority network link as a backup to normal heartbeat channels. Low-priority links are typically configured on a public or an administrative network. This typically results in a completely different network infrastructure than the cluster private interconnect, and reduces the chance of a single point of failure bringing down all links. The low-priority link is not used for cluster membership traffic until it is the only remaining link. In normal operation, the low-priority link carries only heartbeat traffic for cluster membership and link state maintenance. The frequency of heartbeats drops 50 percent to reduce network overhead. When the low-priority link is the only remaining network link, LLT also switches over all cluster status traffic. Following repair of any configured private link, LLT returns cluster status traffic to the high-priority link.

LLT links can be added or removed while clients are connected. Shutting down GAB or the high-availability daemon, (had), is not required.

To add a link

To remove a link

See the lltconfig(1M) manual page.

Changes take effect immediately and are lost on the next reboot. For changes to span reboots, you must also update the /etc/llttab file.


LLT clients will not know the cluster status until you only have one LLT link left and GAB declares jeopardy.