When I join the team I have no knowledge on VCS, like zero knowledge and then I came to know a few stuffs like bringing online and clearing faulted resources and groups and that’s it, I didn’t even care about the rest because usually that’s the only alerts we get that is the only thing you need to do.

But what if one of the system crash and when it comes up all the groups and resources went offline, how would you know on which system it should be online?

So I asked my Team lead and here’s what I’ve learned. There is no primary/secondary concept in VCS but you can mention the priority on which host the service group will come up with AutoStartList and SystemList and it’s more complex than I thought :D

SystemList

The SystemList attribute designates all systems that can run a particular service group. VCS does not allow a service group to be brought online on a system that is not in the group’s system list. By default, the order of systems in the list defines the priority of systems used in a failover. Lower numbers indicate a preference for the system as a failover target.

for example

SystemList = { SystemA, SystemB, SystemC }

configures SystemA to be the first choice on failover, followed by SystemB and then SystemC.

Note that you must define this attribute prior to setting the AutoStartList attribute.

AutoStartList

List of systems on which, under specific conditions, the service group will be started with VCS (usually at system boot). For example, if a system is a member of a failover service group’s AutoStartList attribute, and if the service group is not already running on another system in the cluster, the group is brought online when the system is started.

VCS uses the AutoStartPolicy attribute to determine the system on which to bring the service group online.

AutoStartPolicy

Sets the policy VCS uses to determine on which system to bring a service group online if multiple systems are available.

This attribute has three options:

Order (default)—Systems are chosen in the order in which they are defined in the AutoStartList attribute.

Load—Systems are chosen in the order of their capacity, as designated in the AvailableCapacity system attribute. System with the highest capacity is chosen first.

Priority—Systems are chosen in the order of their priority in the SystemList attribute. Systems with the lowest priority is chosen first.

Example:

In the below example the priority on which group unix1 should be online is at system1

view /etc/VRTSvcs/conf/config/main.cf

group unix1 (
SystemList = { system1 = 0,  system2 = 1 }
AutoStartList = { system1 ,  system2 }
)

system1:# hagrp -display unix1 |grep -i autos
smjrskt1     AutoStart             global      1
smjrskt1     AutoStartIfPartial    global      1
smjrskt1     AutoStartList         global      system1      system2
smjrskt1     AutoStartPolicy       global      Order

I still have a lot to learn and should learn it from scratch, problem is I don’t have much resources