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To Cluster or Not to Cluster?  That is the Question.

Posted on 2014-07-17
Medium Priority
Last Modified: 2014-07-22
Some background...I just received two new servers and a SAN.  The servers are running VMware and are setup as two nodes in a clustered environment.  While I got some crash-course training for VMware, I am a fresh fish to this game.  I am setting up a new domain infustructure using all VMs running Windows Server 2012.  We are a small shop that operates from 8-5 so if there is some down time for maintenance after hours or the weekend it is not a big deal.  

I am in the process of getting setting up a Server 2012 File Server, and Exchange 2013 Server and a SQL 2014 Server.  In your opinion, would you you create clusters for the File Server, Exchange Server and SQL Server?  To do so, I would need to purchase an additional license for SQL and Exchange.  

If my logic is correct, the clustered environment of these servers would protect me against an software OS failure.  I already have vSphere HA so if one of my ESXi hosts goes down then the VMs would be transfered to another ESXi host.  Therefore, the Windows clusters don't provide me any advantage if a hardware failure takes place.  

So once again, would you run these Windows Servers in a cluster or just as a single VM?

I appreciate all your feeback!
Question by:csimmons1324
LVL 19

Accepted Solution

Miguel Angel Perez Muñoz earned 500 total points
ID: 40202344
Thats depends what kind of failures what want to be protected:

You can virtualize and create a "cluster" with both servers running Windows 2012, you will get protected against hardware failures but if one service fail, this configuration causes a outage. Server running virtual machines fails, all machines will be moved to the other. You can use vmware or hyper-v, is quite similar.
Or can create an old style cluster, clustering your SQL, Exchange and file services and get redundancy if server or service fail, but you need twice licences of all, and some of them more expensive (Exchange requires enterprise).

Assisted Solution

by:Philip Portnoy
Philip Portnoy earned 500 total points
ID: 40202345

please note that cluster does not only provide High availability. It also makes day-to-day maintenance easier.
For SQL Server - if you're financially capable to purchasie 2 Enterprise editions than I'd recommend you to build Always On HA cluster  - again, you'll get easier maintenance, you'd be able to run backups and reporing on secondary server.
If you have Standard edition - then 1 SQL Server with vMotion for HA will be enough.

For file server having a cluster if you're using just 1 SAN is the best way to go, though if you have multiple SANs/sites I'd recommend using DFS replication.

For Exchange there's no such thing as a cluster (in a way we're used to treat it). But I'd recommend setting up Database Availability Group - again, you get easier maintenance and a chance to balance the load a bit.

Expert Comment

by:Philip Portnoy
ID: 40202353
Statement used previously by Miguel Angel Perez Muñoz is false - Exchange does NOT need Enterprise for HA.
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Assisted Solution

by:Mayson Arnagiri
Mayson Arnagiri earned 500 total points
ID: 40202368
Documentation below can assist with this,



My personal view - if you have HA, and so few servers to implement, create the VM's on the hosts and load balance between the 2. As long as HA and your network interfaces are configured correctly there can be much resilience and a cost effective implementation.
You need to also ensure that your network layer is configured correctly. The hosts and the SAN configured with gig fiber channels, and these connect back to the network layer how? this must have fail-over structure in place (in case of network issues)

Good luck...

Author Comment

ID: 40202370

I do only have one SAN.  As for Exchange....to use the DAG do I am assuming that I need multiple Exchange servers, correct?

Expert Comment

by:Philip Portnoy
ID: 40202386
Yes, you will need 2 Exchange servers (and 2 Exchange licenses, though Standard is enough if you're not planning on having >10 databases or some other complex stuff).
You can balance only databases, or you can make second server a CAS as well. In this case you will need NLB (which might be just any Windows system or special hardware if you have it) to balance user HTTPs requests between servers.

Author Comment

ID: 40202429

I am new to a A LOT of this stuff (VMware, Windows Clusters, Network Layers, etc.).  All of the VMware / HA stuff was setup by a consultant onsite while he gave me some basic training on VMware.  The SAN and ESXi hosts are configured using iSCSI connections using two NICs in each host running through a gigabit switch.
LVL 70

Assisted Solution

by:Scott Pletcher
Scott Pletcher earned 500 total points
ID: 40202465
You can cluster SQL standard in a 2-note active-passive setup and that would require only a single SQL license.  I suspect that's true for Exchange as well, since only one node is ever active at any given time, but I can't say that for sure.

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