veritas cluster-LLT configuration & Removing LLT links

In Veritas cluster, When you add or remove LLT links, you need not shut down GAB or the high availability daemon(HAD). Your changes will be taken effect immediately.But it will be lost on the next server reboot. To make your changes to persist, you have to update in /etc/llttab where all the cluster communications are present.

Here we will see how to add new link and remove the existing hear-beat Links  in  veritas cluster nodes on the fly without any impact.

To add a new LLT link:
Log in to one of the nodes in the cluster as the root user and run the following command:

# lltconfig -d device -t device_tag

Where: -t devtag is the device tag used to identify the link -d device is the network device path 

See the lltconfig for more options and detailed information.For example:

# lltconfig -t e1000g2 -d
/dev/dlpi/en:2

If you want to configure the link under PrivNIC or MultiPrivNIC as a failover target in the case of link failure, modify the PrivNIC or MultiPrivNIC configuration as follows: 

# haconf -makerw
# hares -modify resource_name Device device device_id [-sys hostname]
# haconf -dump –makero

The following is an example of configuring the link under PrivNIC or MultiPrivNIC.Assuming that you have two LLT links configured under PrivNIC as follows:

PrivNIC ora_priv
(
Critical = 0
Device@mygz1 = { e1000g1 = 0, e1000g2 = 1 }
Device@mygz2 = { e1000g1 = 0, e1000g2 = 1 }
Address@mygz1 =
"192.168.12.1"
Address@mygz2 = "192.168.12.2"
NetMask ="255.255.255.0"
)

To configure the new LLT link under PrivNIC, run the following commands:

# haconf -makerw
# hares -modify ora_priv Device e1000g1 0 e1000g2 1 e1000g3 2 -sys mygz1
# hares -modify ora_priv Device e1000g1 0 e1000g2 1 e1000g3 2 -sys mygz2
# haconf -dump -makero

The updated PrivNIC resource now resembles:

PrivNIC ora_priv
(
Critical = 0
Device@mygz1 = { e1000g1 = 0, e1000g2 = 1, e1000g3 = 2 }
Device@mygz2 = { e1000g1 = 0, e1000g2 = 1, e1000g3 = 2 }
Address@mygz1 =
"192.168.12.1"
Address@mygz2 = "192.168.12.2"
NetMask ="255.255.255.0"
)

Removing LLT links:
If you want to remove the link which is configured as a PrivNIC or MultiPrivNIC resource, then you need to modify the resource configuration after removing the link.

To remove LLT links:
Log in to one of the nodes in the cluster as the root user and run the following command:

# lltconfig -u device_tag

Where: -u devtag is the device tag used to identify the link you want to removeSee the lltconfig(1M) for more options and detailed information.For example:

# lltconfig –u e1000g3

If you have configured the link under PrivNIC or MultiPrivNIC as a failover target in the case of link failure, modify the PrivNIC or MultiPrivNIC configuration as follows:

# haconf -makerw
# hares -modify resource_name Device link_name device_id [-sys hostname]
# haconf -dump –makero

For example, if the links e1000g1, e1000g2, and e1000g3 were configured as PrivNIC resources, and you want to remove e1000g3:

# haconf -makerw
# hares -modify ora_priv Device e1000g1 0 e1000g2 1
Where e1000g1 and e1000g2 are the links that you want to retain in your cluster.
# haconf –dump  -makero

Please do not forget to update /etc/llttab. 

Thank you for reading this article.Please leave a comment if you have any doubt ,i will get back to you as soon as possible.