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Single Server ---> DAG - 3.Jan.2012 7:27:48 AM

bvadmin

Posts: 5
Joined: 15.Dec.2010
Status: offline

Hello All and Happy New Year,

I have a quick questions to ask some helpful DAG expert,

I currently have 1 Exchange server running, this is a Windows Server 2008 R2 Enterprise with Exchange 2010 Standard SP1, now this server has all the Exchange roles currently installed.

Now my question is in order to achieve High Availability do I need an additional 2 servers along with current server or do I just need 1 extra server or maybe 3 extra, I am a little confused regarding the Client Access and Hub Transport roles and requirements.

Any help or pointers would be great.

Post #: 1

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RE: Single Server ---> DAG - 3.Jan.2012 10:32:20 AM

de.blackman

Posts: 3243
Joined: 4.Apr.2005
From: Toronto, Canada
Status: offline

OK lets begin with some basic requirements - In order to have DAG, you need a minimum of 2 servers running the mailbox role. Secondly, if you would like to co-locate the CAS and hub transport roles on the same servers as the mailbox role, this IS possible UNLESS but that means you will have no high availability for the CAS and HT roles. In order to achieve high availability for those roles, you need to load balance them either using Windows NLB or hardware load balancer (hardware recommended by Microsoft). Now here is the problem - If you want to use Windows load balancing with CAS\HT then you cannot colocate them with the mailbox role because DAG and Windows NLB cannot be placed on the same server!

In conclusion, I see you having the following options:

If you want complete high availability of the three roles then:

Install a second server with all three roles and purchase a hardware load balancer for the CAS\HT roles. Implement DAG for the mailbox role.
Install a new mailbox server and then install 2 servers running CAS+HT (total of 3 new servers). Configure the CAS\HT servers with Windows NLB and the 2 mailbox servers with DAG.

_____________________________

Ibrahim Benna - Microsoft Exchange MVP
Forum Moderator
Navantis

(in reply to bvadmin)

Post #: 2

RE: Single Server ---> DAG - 3.Jan.2012 10:38:44 AM

bvadmin

Posts: 5
Joined: 15.Dec.2010
Status: offline

Great Thank You, that's what I needed :)

Can you recommend and hardware load balancer that will do the job well?

(in reply to de.blackman)

Post #: 3

RE: Single Server ---> DAG - 3.Jan.2012 10:42:27 AM

de.blackman

Posts: 3243
Joined: 4.Apr.2005
From: Toronto, Canada
Status: offline

Hardware load balancers are quite pricy so you have to work with your budget. I have clients that use CoyotePoint and others using F5 BigIP. If your machines are virtual you can consider getting a virtual HLB as i think F5 have one.

_____________________________

Ibrahim Benna - Microsoft Exchange MVP
Forum Moderator
Navantis

(in reply to bvadmin)

Post #: 4

RE: Single Server ---> DAG - 3.Jan.2012 10:49:21 AM