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Choose Best CLustering And Quorum Plan for A.G. Always on


#1

Hi
again about Always on
we have 3 servers. I face with 2 plan to cluster servers in order to run Always on .
But I cant set Cons And Pros About these plans.
Please Help me.

we have sql server 2014 And windows server 2008 R2

And I say that we planed to have 2 availability Group :smile:
Availability group 1 : Db1 , DB2 , DB3 , DB4 (Between server1 And HA)
Availability group 2 : DB5 (Between server2 And HA)

And
In first step , most probably (as is showed in figures) we dont have DR.
Thank you


#2

I hope I understand you correctly, both your plan will work, it just the level of resilience here. I would assume the HA server is your DR server, in the case of losing 1 server (either server1 or server2), everything still works (given HA server can handle the load).

However, if you lose server1 and HA server, you will lose DB 1 to 4. In your first option, you can still have all DBs running in server2.

If you are still in planning phase I would rather use Win 2012 (or 2012 R2), given that it got better option for your MS cluster (last man stand), where you can set node majorly and even if you lose 2 of the nodes, you cluster is still up (more design needs to put to that).

Hope this helps


#3

In first step we dont have DR.
in this time : On one datacenter , we have only HA .
in addition server-2 And server-1 are separated complataly.
you suppose
In first step :
we have 2 server : server 1 And server HA. And we want server 1 will be Main replica . that s all. what is the best config Quroum and vote for this 2 server?

After that :
on base of budject limitation , we want to use server HA as second replica for another server (server 2) .
in means server-2 is main replica And Server-HA in secondary replica.
then we have 3 server and 2 A.G.
in this case :
what is the best cluster pland and config Quroum and vote for this 2 server?
Thank you


#4

Hi,
I'm not sure if I follow, can you please state out how many servers you have and where their location? Also what type of HA method you have in mind?

If I understand you correctly, your first "step" or "option" is having 2 servers server 1 and HA server, I assume you still talking about AG, then the quorum you mention here is the MS cluster quorum? If you are using Win 2012, you can leave it as default given you are on 1 data center, or you can have file share witness if you really wanted.

in your second option, I am totally lost, can you please help to state out the server role so that it would be easier to understand.

Rgds,


#5

Sorry For my Vague Question.
Forget my plans And our Facilities . Let us to go step by step :

Step 1 :
It is totally :smile:
We have 2 Practical Main server. (Server1 And Server2)
- Server1 has 4 databases And server2 has 1 dataabse.
- We have Sqlserver 2014 And Windows server 2008 R2 (unfornatuly we cant go to 2012 R2)
And we need a Plan for HADR. (based on Always on-Availability Group)
What is the best Simple and stable Plan ?
Thank you for your kindness dennisc.


#6

Sure, let go from that....

with 2 servers on the same data center, given I do not know your other requirement, you can use failover cluster or always on AG, if your choice is AG, then it just a simple MS cluster then setup always on in SQL and pretty much off you go. In terms of MS cluster, you would need to have a file share witness (on another server) or other form that you see fit to provide quorum in case one of the server fails. AG will work its way based on the MS cluster and failover itself (given you configured sync mode).

If you are not fixed with AG (from whatever reason), you can simply go for SQL failover cluster, given there are only 2 servers, it might be easier that way, but you will need a share storage (maybe that is the limitation?)

That is more on the HA side, since AG in sync mode should considered to be HA, not DR.

Hope this helps.