How to add a low or high priority heartbeat link to LLT without rebooting the nodes.

The following steps configure a heartbeat (HB) link using the lltconfig command on a running cluster. The command can be used to create a high or low-priority heartbeat link on an existing network interface card (NIC).

 

The /etc/llttab file can then be edited for a persistent configuration after future reboots. This method saves from performing a reboot.

Example of current /etc/llttab configuration and lltstat -nvv output:

# cat /etc/llttab

set-node node1
set-cluster 555
link eth1eth-00:0C:29:0F:B6:E8 - ether - -
link eth2 eth-00:0C:29:0F:B6:F2 - ether --

# lltstat -nvv

LLT node information:
   Node                State    Link  Status  Address
  * 1 node1            OPEN
                                 eth1  UP      00:0C:29:0F:B6:E8
                                 eth2  UP      00:0C:29:0F:B6:F2
    2 node2              OPEN
                                 eth1  UP      00:0C:29:AC:3F:BF
                                 eth2  UP      00:0C:29:AC:3F:C9


Example of creating a low-priority HB line on the "public" NIC:

# lltconfig -t eth0 -d eth0 -l

Warning: If the -l is omitted, the HB link will be a high-priority link.

After the first node is configured, the lltstat -nvv output will show the added heartbeat:
 

# lltstat -nvv

LLT node information:

Node State Link Status Address

* 1 node1 OPEN

eth1 UP00:0C:29:0F:B6:E8

eth2 UP00:0C:29:0F:B6:F2

eth0 UP00:0C:29:0F:B6:DE

 

2 node2 OPEN

eth1 UP00:0C:29:AC:3F:BF

eth2 UP00:0C:29:AC:3F:C9

eth0DOWN

 

Repeat the command on the second node.

# lltconfig -t eth0 -d eth0 -l

 

The lltstat -nvv output showing the second node linked.

 

# lltstat -nvv

LLT node information:

Node State Link Status Address

1 node1 OPEN

eth1 UP00:0C:29:0F:B6:E8

eth2 UP00:0C:29:0F:B6:F2

eth0 UP00:0C:29:0F:B6:DE

 

* 2 node2 OPEN

eth1 UP00:0C:29:AC:3F:BF

eth2 UP00:0C:29:AC:3F:C9

eth0 UP00:0C:29:AC:3F:B5

Repeat the step to configure the heartbeat link for each additional node in the cluster.

Delete a heartbeat

In order to delete a heartbeat, first make sure there are two other heartbeats running, otherwise a jeopardy condition will exist. Jeopardy condition means VCS will not perform failover functions in an event of a fault.

# lltconfig -u [devtag]

In most cases, the devtag is the same as the network interface used for the heartbeat, e.g.