January 19, 2014 at 9:13 am
Hi,
I am trying to understand Always On. How can you add additional drive in Always on like in Clustering. How to increase memory of the instance.
If you dc any changes in Primary is it replicates in all 4 replicas or shall we mention that I want only for 1 replica or some thing like that.
Please let me know.
January 19, 2014 at 9:28 am
Availability Groups are not in any way like clustering. You're defining various systems that share no hardware at all to belong to an Availability Group. Then, you can define a database to take part in the Availability Group. It's a database, by database proposition. So, if you want to modify a given server in the availability group, like add a disk, just take that server offline and add the disk. If it's the current primary you'll have to do a failover to one of the secondaries, but that's the purpose of having availability groups. After the modification, you can fail it back over or not. But at no point are these shared resources like they are in Clustering where the servers have to match and all storage is common. You can even have an availability group set up between your local machine and a virtual machine in Azure. They don't share, they just have to be able communicate with each other.
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January 20, 2014 at 6:33 am
The only time shared storage comes into play is when you incorporate an FCI as an AlwaysOn replica
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February 8, 2014 at 6:08 am
Thank you. I didn't get any chance to implement that.
I have one more question what about the"" Listner". In some blogs they are saying listener is optional in Always on but if you don't have listener how can it check the failover.
February 8, 2014 at 11:11 am
ramana3327 (2/8/2014)
Thank you. I didn't get any chance to implement that.I have one more question what about the"" Listner". In some blogs they are saying listener is optional in Always on but if you don't have listener how can it check the failover.
The listener is optional, it provides a central client access point into the AO group database(s). It does not control failover of the AO group, rather it's the other way around. If configured the listener will be failed over by the cluster service when the primary replica changes in the AO group.
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