What happens when you online a SG
– When a service group is brought online, all the resources in that service group are brought online one by one starting from the child resource.
– Depending on the dependencies defined, when all the resources are brought up, the service group becomes online.
– In order to bring a failover service group online, VCS must verify that all non-persistent resources in the service group are offline everywhere in the cluster. If any non-persistent resource is online on another system, the service group is not brought online.
– A service group is considered online if all of its non-persistent and autostart resources are online.
– The state of persistent resources is not considered when determining the online or offline state of a service group because persistent resources cannot be taken offline. However, a service group is faulted if a persistent resource faults.
How to online a Service Group
To bring a service group online, you can use either of the below hagrp commands.
1. To bring Service group online on particular system in the cluster.
# hagrp -online [group] -sys [hostname]
2. To bring the service group online busing -any switch.
The -any option brings the service group online based on the group’s failover policy.
# hagrp -online [group] –any
What happens when you offline a SG
– When a Service Group is taken offline, all the resources are taken offline one by one starting from the parent to the last child resource.
– The highest (parent) resources in each branch of the resource dependency tree is taken offline first progressing down the resource dependency tree to the lowest (child) resources.
– Persistent resources cannot be taken offline. Therefore, the service group is considered offline when all nonpersistent resources are offline.
How to offline a Service Group
To take a service group offline, you can use either of the below hagrp commands.
1. To bring Service group offline on particular system in the cluster.
Provide the service group name and the name of a system where the service group is online.
# hagrp -offline [group] -sys [hostname]
2. To bring the service group offline using -any switch
The -any switch takes a failover service group offline on the system where it is online. All instances of a parallel service group are taken offline when the -any switch is used.
# hagrp -offline [group] –any
VCS (Infoscale Availability) – Difference Between Frozen and TFrozen attributes
VCS (Infoscale Availability) : How to freeze a Service Group