AlwaysOn local HA with second site automatic failover.

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AlwaysOn local HA with second site automatic failover.

PHXHoward

SSCrazy Eights

Points: 8388
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April 3, 2014 at 12:54 pm

#306055

I'm looking for a solution to have cross data center automatic failover in the event of a data center loss for highly critical databases. I would like to have local HA and also automatic failover to the DR site. This does not seem possible with AlwaysOn.
Is my only option for automatic cross data center failover to build a node in one data center and a node in the other data center with a node/FS at a third data center in order to maintain quorum? I'd like to have local HA in the mix but that doesn't seem possible.
What pattern do you suggest for the highest data security and also availability?
Thanks

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SQLBuddy123 One Orange Chip Points: 28294 More actions · Answer 1

When you say "cross data center automatic failover" are you refering to failing over whole instance\bunch of databases\a single DB ?

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SQLBuddy

PHXHoward SSCrazy Eights Points: 8388 More actions · Answer 2

I'm thinking of partially contained database so in the case the instance doesn't need to come across, just the database with the contained users.

Is it true that I would want one cluster node in one data center and the second cluster node in the other data center with a third node in a third data center in order to maintain quorum?

SQLBuddy123 One Orange Chip Points: 28294 More actions · Answer 3

PHXHoward (4/3/2014)
I'm thinking of partially contained database so in the case the instance doesn't need to come across, just the database with the contained users.
Is it true that I would want one cluster node in one data center and the second cluster node in the other data center with a third node in a third data center in order to maintain quorum?

If it's a single database, then I don't think that's needed. Just use Failover Clustering in Data Center A and setup DB mirroring on that DB for the remote Data Center B.

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SQLBuddy

Perry Whittle SSC Guru Points: 233858 More actions · Answer 4

PHXHoward (4/3/2014)
I'm looking for a solution to have cross data center automatic failover in the event of a data center loss for highly critical databases. I would like to have local HA and also automatic failover to the DR site. This does not seem possible with AlwaysOn.

To have local HA at the instance level would require a clustered instance, this may only participate in an AO group for manual failover. Given this, it doesn't meet your requirement.

PHXHoward (4/3/2014)
Is my only option for automatic cross data center failover to build a node in one data center and a node in the other data center with a node/FS at a third data center in order to maintain quorum? I'd like to have local HA in the mix but that doesn't seem possible.
What pattern do you suggest for the highest data security and also availability?
Thanks

You may still achieve local HA using alwaysOn by having a secondary replica on the primary site configured for automatic failover.

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"Ya can't make an omelette without breaking just a few eggs" 😉

Jared SSC Guru Points: 61793 More actions · Answer 5

First, make sure this database is not involved in any cross-database or distributed transactions. They are not supported with AO. Have you thought about doing a geo-cluster? We are currently doing this with one of our applications. It is a 3-node cluster with 1 node being in our DR site. For the storage, we use Site Recovery Manager (SRM).

Jared
CE - Microsoft