How to Configure Database Availability Group in Exchange Server 2010 « Exchange Server 2010 Learning Guide

Exchange Server 2010 Learning Guide

August 2, 2011

How to Configure Database Availability Group in Exchange Server 2010

Filed under: Exchange Server 2010 — exchange2k10 @ 12:20 pm

As we all know, we have a brand new high availbility feature called Database Availabilty Group aka DAG inExchange Server 2010, replaced the legacy High Availability concepts like CCR and SCR. We dont have

LCR, CCR, SCC or SCR in Exchange Server 2010.

As like CCR, DAG uses the same asynchronous log file shipping technology to synchorinize the log filebetween Active Mailbox Database copy and the Passive Mailbox Database Copy. In CCR, if any problem

occurs to single mailbox database , all the databases on the active server will be failover to passive one. InDAG, we have the option to activate the affected mailbox database on the other member server.

As like SCR, DAG will help in performing the site resilency over different sites. Disaster Recovery site

configuration are not difficult as like exchange server 2007. DAG replication occurs by TCP\IP, where in, ithappened using SMB, server message block in exchange server 2007

In this post, we are going to look at, how to configure the Database Availability Group and in the second post

of the same, we will look at how to manage Database Availability Group

I’ll add a new post on how Database Availability Group works in my next series of post related to DAG

Basic Terms on Database Availabiltity Groups

Database Availability Group – Database Availability Group is a group of Mailbox servers that holds the set

of replicated databases. We can have up to 16 Mailbox Servers together to make the Database replicatedbetween them

Database Copies – Mailbox database copy is a mailbox database (.edb files and log files) that is either active

or passive copy of the mailbox database, we can add the database copies in different server, where in total wecan have 15 database copies together and set the activation preference for all the database copies to at whatsituation particular copy needs to be active

Switchover – A switch over is a manual activation one or more databases when failure occurs

Failover – A failover is an automatic activation of one or more databases after failure

Shadow Redundancy – Shadow redundancy – a transport feature that provides redundancy for messages for

the entire time they are in transit

Incremental deployment – the ability to deploy high availability or site resilience after the exchange isinstalled

High Availability – We will take about HA in lot of situation, HA is a solution that provide data availability;service availability and automatic recover from site failures

How to Configure Database Availability Group in Exchange Server 2010 ... http://exchange2k10.wordpress.com/2011/08/02/how-to-configure-databa...

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Disaster Recovery – It is a procedure used to manually recover a Server\Database level failure

Site Resilience – Site Resilience is a disaster recovery solution used for recovery from site failure

Active manager – Exchange component that manages switchovers and failovers, runs on every servers on

the DAG, this selects the best available copy on failovers, there are two Active Manager Roles are there;Primary Active Manager and Secondary Active Manager

Primary Active Manager – runs on the node that owns the cluster group, gets topology change notification,

this reacts to server failures, if any problem to active copy this PAM selects the best database copy on switchover or failover

Standby Active Manager – runs on every node on the DAG, responds to the queries about which server hosts

the active copy of the mailbox database

I added new concepts or terms related to exchange server 2010 in my previous post, you can have a look athere

Demo

For this demo, I’m having 4 Machines

Test-EX-DC01 – My Domain Controller – Domain Name: Chennai.Com

TEST-EX-MCH1 – Exchange 2010 with Mailbox, Client Access, Hub Transport Server roles – DAG Member1

TEST-EX-MCH2 – Exchange 2010 with Mailbox, Client Access, Hub Transport Server roles – DAG Member

2

TEST-EX-CH01 – Exchange 2010 with Client Access and Hub Transport Server roles – File Share Witness

TEST-EX-CH02 – Exchange 2010 with Client Access and Hub Transport Server role

Prerequisites to configure DAG

Before informing the prequsites, I’ll explain my current setup.

I have a domain controller named TEST-EX-DC01 and the domain name is chennai.com. Also I have two

mailbox servers TEST-EX-MCH1 and TEST-EX-MCH2 installed with Mailbox server role, Client AccessServer role and the Hub Transport Server Role. I have two other machines installed only with Client Accessand Hub Transport Server role and the computer names are TEST-EX-CH01 and TEST-EX-CH02, where i’m

goign to have the FSW in TEST-EX-CH01.

We need atleast two mailbox Server, which holds any servers roles installed in that machine

One Hub Transport Server, which hold the File Share Witness Directory and the Admin should have owner

permission on the FSW folder

To configure this DAG, we have two mailbox Servers and they arementioned below


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Also, we have one mailbox database on each server, that we are going to configure the Database copies ofMailbox Database 1 on first server to be available in Second server and Mailbox Database 2 on second serverto be available in first server

Steps involved in Database Availability Group configuration

Create a File Share Witness folder on the witness server (in our case TEST-EX-CH01)1.Create the Database Availability Group (DAG-101 is our DAG name)2.

Configuring full access for the DAG name over the FSW folder3.Configure the Members servers which are to be included in the DAG to function as a unit4.Configure the Mailbox Database copies to be available on the other node5.

Check the Mailbox Database Copy status are healthy6.

Create a FSW on the witness server

Login to Hub Transport Server (TEST-EX-CH01) and create a share folder with the nameWitness_Directory and assign owner permission for the account which is used to configure the DAG. We

can create the shared folder in any drive, for my test environment, I created the FSW folder in C drive

Create the Database Availability Group

To create a new DAG, Point to Organization Configuration -> Mailbox Database -> Database Availability

Group and in the action pane, click New Database Availability Group

Provide the below information as shown in the figure

On the next page click new to create the DAG with the name DAG-101


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Below figure shows the DAG, this is configured in my Test Environment

Configuring full access for the DAG name over the File Share Witness folder

After creating the DAG, an AD object will be created for the DAG name, where we have to grant full accesspermission for the DAG$ object on the File Share Witness folder

Go to the FSW folder and grant full access permission for the account “DomainName\DAG-Name$” if notwe will get the below warning while adding Members to the DAG

Error:

The file share witness path ‘\\TEST-EX-CH01.CHENNAI.COM\DAG-101.CHENNAI.COM’ exists, but its

permissions are not set correctly. The account ‘DAG-101$’ needs to have Full Access.

Warning:

The operation wasn’t successful because an error was encountered. You may find more details in log file

“C:\ExchangeSetupLogs\DagTasks\dagtask_2011-07-31_19-38-36.592_add-

databaseavailabiltygroupserver.log”.

Configure the Members servers which are to be included in the DAG to function as a unit

To add the members to the newly created Database Availability Group, Point to Organization Configuration-> Mailbox Database -> Database Availability Group -> Select the DAG Name and in the action pane select

Manage Database Availability Group Membership


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On the opened management console, add the servers, which are all going to be member of this Database

Availability Group and click next to continue

To perform the same on Exchange Management Shell command:

Add-DatabaseAvailabilityGroupServer -Identity ‘DAG-101′ -MailboxServer ‘TEST-EX-MCH1′

Add-DatabaseAvailabilityGroupServer -Identity ‘DAG-101′ -MailboxServer ‘TEST-EX-MCH2′

Above figure shows the completion of adding DAG group members to the newly created DAG “DAG-101″

Below figure shows the DAG status with the Name, Member Servers, Witness Server and Witness Directory.On the bottom of the figure it shows the DAG networks which are available for the use of the DAG function.Replication of log files will be used by both the private and public Nics, where can set the replication to be

allowed only using the particular network. We will discuss this on, how to manage DAG in other post


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Configure the Mailbox Database copies to be available on the other node

As I mentioned earlier, I have two mailbox databases with the name “Mailbox Database 1″ and “MailboxDatabase 2″ one on TEST-EX-MCH1 and other on TEST-EX-MCH2. I’m going to make the database“Mailbox Database 1″ in TEST-EX-MCH1 as available as a mailbox database copy on TEST-EX-MCH2 and

vice versa

To configure the mailbox database copy on other server, point to Organization Configuration -> MailboxServer -> Database Management -> right click the mailbox database on the first server and select Add

Mailbox Database Copy


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Select the server name in which the first mailbox database to be available as a copy on the passive server.

Set the Activation Preference Number to set at what level this copy has to mount. Let’s take if you have 5available copies and if you set the activation preference number as 4. If the first copy failed for some reason,the second will give a try to mount and if any problem, the third available copy will give a try to mount and

for any reason the third fails, the fourth copy will try to mount.

Below shows the completion of Mailbox Database copy wizard


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Below figure show the status of “Mailbox Database 1″ which is mounted on TEST-EX-MCH1 and holds the

passive copy available on the TEST-EX-MCH2 Server and the copy status of the database copy is health onthe second server.

For the second mailbox “Mailbox Database 2″, we did configure the Mailbox database copy to be availableon the first server and it hold only one copy which is mounted the second server as shown the below figure


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Check the health of Mailbox Database Copy status

In Exchange server 2007, we use the storage group copy status command to check the help of a Cluster

Mailbox database status for example

Get-StorageGroupCopyStatus –Identity “Cluster Name”

In exchange server 2010, we don’t have storage groups; we can check the heath of the DAG using Mailbox

Database Copy Status command, for example

Get-MailboxDatabaseCopyStatus –Sever “Server Name On the next part we will look at HOW TOMANAGAE DAG Like, how to check the Database Copy Status Health, how to perform a failover, how to

activate the second copy and few configurable parameters available in Database Availability Group

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How to Configure Database Availability Group in Exchange Server 2010 « Exchange Server 2010 Learning Guide