Exchange 2013 High Availability

The CAS Array no longer exists in Exchange 2013

You may refer to deployment assistance from Microsoft.

http://technet.microsoft.com/en-US/exdeploy2013/Checklist?state=2284-W-AgAEAAAAQAAAAAEAAQAAAA~~

Yes i know about the cas array i wrote it wrong. Thanks ,

Any ideas about the load balancer ? Can i use windows load balancer ? Or maybe something else?


Thanks

your environment would be small. you can use WLB (Windows Load Balance ) otherwise, you can go to HLB (Hardware Load Balance)

Please note: Even Microsoft also recommended to HLB, It s up to company cost


Thanks

I would drop the idea of two separate servers with the CAS role and just have everything on two servers. Then spend the money on a hardware load balancer (or a virtual). Something like a Kemp. They have templates for Exchange 2013 and I had it running for a client just yesterday in less than 20 minutes, including download time of the VM.

Simon.

Hello Simon ,

Only 2 Servers ? You mean 2 all in one servers?

In specs of performance , is this ok to have all in one servers ? I will have Virtual machines for this installation and about 1500-2000 users for start.

In terms of high availability if one server goes down than the other will take the DAG and continue to work ?


Thanks

For that number of users, with the appropriate hardware you could probably get away with two servers, although you may want three. All three having all of the roles. That will allow you to run a/a/p on the DAG, and if a server goes down, you still have two servers in production.

1500 users on a single server is perfectly possible with Exchange 2013. Hub/CAS functionality is very light on hardware, the bulk of the work is done on storage in the mailbox role.

The fact that it is VM means nothing. You still need to ensure the underlying storage configuration is correct.

Simon.

Hello ,


Correct me if im wrong but if i want to go with the windows NLB i must have cas and mbx roles in different machines ?


Thanks

That is correct. However WNLB sucks quite badly, the Exchange product team don't recommend it. I actually refuse to deploy it - and never include it in any of the designs I do.

That is why I said to save the cost of the licences (for Windows and Exchange) and put the money to a load balancer. A load balancer like a Kemp VM will be a lot more reliable than the junk called WNLB and it will then be trivial to add additional Exchange servers as the platform grows.

Simon.

Hello Simon ,

Do you use 2 Kemp Virtual Load balancers for HA ? If you have one and goes down then nothing works right ?


Thanks

If you want complete redundancy then yes you would use two Kemps. They would be on two different physical hosts.

Simon.

Im planning an Exchange 2013 Installation with maximum high availability and easy upgrade when users are getting more and more.

Depending on the amount of users that you are supporting will govern the amount of mailbox servers that you need.   One of the best practices is to segregate the different departments or roles.   When I do a implementation I usually start with a database for Check Writers (CEO etc.), then a database for Managers and then a database for the rest of the users.   But, this can change based on the number of users.   Then there you can decide which databases that you want to put as database copies.   Microsoft recommends that you have at least 3 mailbox servers in a DAG.   You can do it with only two but that leads to Murphy's Law.   Having three is a better implementation.  When I did a migration from Novell Goupwise to Exchange Server 2010, we implemented 2 physical Mailbox servers and 2 virtuals.  

Exchange Server 2013 has eliminated the CAS array.   The CAS array was an object that was put into the Configuration partition in Active Directory.   It was used to identify the Server Cluster that is created using Network Load Balancing (NLB).   Now the CAS servers are identified by a GUI.  So, we still install NLB on all of the CAS members and set up the cluster and it recognizes the Cluster.   I have a client in the Caymans that is using 3 CAS servers with NLB.   They were using a hardware load balancer before.   Everything is failing over like it was designed.  

Exchange Server 2013 has built in Anti-SPAM and Mal-ware protection is used to the implementation of ForeFront Protection for Exchange.   You can implement the Edge Transport is you like to provide a deeper protection.   With service pack 1 they are supposed to release the Edge Transport for Exchange Server 2013.   Here is an example of what we did for Exchange Server 2010.   We installed the ForeFront TMG , Edge Transport and FrontFront Protection for exchange on two different servers.   Then when implemented Network Load Balancing through the TMG.   This provided redundancy of the Edge and also TMGs.  

So your design would work:

2 CAS
2 Mailbox
TMG + Edge

I would recommend:

3 CAS
4 Mailbox

The biggest expense will be the licensing.   You can use Standard Edition for the CAS , Edge , TMG servers and use Enterprise for the Mailbox servers.   This would be 2008 R2.   If you are going to use Windows Server 2012 then use Standard for CAS, TMG, Edge and Datacenter for the Mailbox Servers.   DAG requires Failover Clustering which is available only on Datacenter in Windows Server 2012.   Enterprise and Datacenter are the choices for Windows Server 2008 R2.  

Let me know if this helpful and if you need anything additional

Thanks,

Michael W Krout, MCSE, MCSA, MCTS, MCITP, CVE 5.0, MCT

Im thinking of 2 servers for each role for Start.

2 CAS to create a cas array and 2 MBX to create DAG.

Also im thinging to install 2 EDGE Servers ( exchange2010) with forefront antispam.

Any ideas about the load balancing of the CAS Array ? Also any tips maybe for the whole installation ?

"DAG requires Failover Clustering which is available only on Datacenter in Windows Server 2012. "

That is wrong.
Failover clustering is available in Windows 2012 standard.

Simon.

Thanks all for your help !! Your advices are important for me .

Anyone knows maybe ZenLoadbalancer ? I read a loooot of good reviews and a lot of them said that it works perfect with Exchange. It is opensource .


Thanks

I have a Zen at home.
It is ok - not as slick as Kemp. A couple of smaller clients use it. The only issue I have seen is it seems to have some problems when a server is rebooted, but if you go in to the config before and manually select a server as being offline, it is fine.

I wrote this on it:
http://exchange.sembee.info/2010/install/loadbalancing2.asp

Simon.

Hello Simon ,


Do you thing that it is better to user ZEn than Windows NLB ? Unfortunately there is no budget for Load Balancer . Maybe Kemp because of the price but again it is too expensive because i need two for HA.

Also i thing that because of Exchange 2013 it is more easy to play with ZEN . No RPC ports only source ip need if i am right.

Thanks

If you want high availability, then you need to pay for it. The design should have been done before the budget. Two Exchange licences are almost the same cost as a virtual load balancer, and if you are licencing Windows as well to host those two additional Exchange servers then the cost isn't that greatly different.
The Exchange product team doesn't recommend the use of WNLB for Exchange services, it sucks quite badly.

I haven't deployed Zen with Exchange 2013, so cannot comment on whether it works better. It should do because everything goes through port 443.

Simon.

Thanks simon .


You are right about the budget but as you probably know  project managers keep asking to build space stations with zero money thats why im looking for the Zen solution.

Another question i have is about the performance.  I mean , if my users become a lot it is better to just increase cpu and memory of each virtual machine or insert in the DAG another mbx and cas server(all in one) ? Any advices about the databases and their sizes?

I try to use the Exchange Calculator microsoft has but it is to much complicated !!

Thanks