Introduction to Database Availability Group in Exchange 2010

Database Availability Group is a group of up to 16 servers that holds the set of replicated Mailbox databases and DAG is the boundary of replication and the failoverswitchover process among those mailbox databases. DAG member servers can be placed in different sites and Database replication can occur over multiple sites.
We will discuss the Database Availability Group concepts on the next 5 chapters, this will be shot introduction on the high availability options that are available in the previous version of exchange 2010.

High Availability in Exchange Server 2003
Exchange Server 2003 depends on Windows Clustering for high availability and that too, the High Availability solution or the redundancy will be available only at the hardware level and not at the database level.

Exchange 2003 cluster nodes shared the same storage system. If the active cluster node suddenly became unavailable, the Exchange Virtual Server (EVS) and any relevant cluster resources would fail over to the passive node and the end users could then continue to access their mailbox.
With Windows Server 2003 Enterprise Edition and Exchange Server 2003 Enterprise Edition, We can set up 8 node cluster for redundancy. With Exchange 2003, we have the high availability option at the server level and not at the StoreDatabase level.

High Availability in Exchange Server 2007
Exchange Server 2007 introduced with the new high availability option both at the server level and the database level. It has 4 High Availability Solution, which uses the continuous replication technology (Asynchronous log file shipping) to have duplicate copy of database at the same server and also at different server. High Availability Solutions in Exchange Server 2007 are

Local Continuous Replication
LCR high availability option can be achieved only at the storage level, Active Copy of the database is replicated to the passive copy of the database using log file shipping, replication of log files will takes inside the server, but to a different disk.

Disadvantage: If the disk goes down, data will be safe at other disk.

Cluster Continuous Replication
Using CCR, High Availability can be achieved at the Server level as well as the storage level, In CCR active copy of the mailbox database will be replicated to passive copy on a Passive node. Using the Windows failover clustering, redundancy will be achieved both at hardware and database level. Using CCR, there is no single point of failure

Disadvantage: No site level redundancy and there is no option to configure a lagged database copy on passive node

Single Copy Cluster
SCC is just like the Exchange 2003 high availability model, where the Single Copy cluster nodes on the cluster shared the same storage device

Disadvantage: We have the high availability option for server and not the database level.

Standby Continuous Replication – SCR is the new high availability model introduced in Exchange 2007 SP1. Data can be replicated to remote site and Site Resiliency can be achieved by shipping log file to another mailbox server in a remote site and there is no need of Windows failover cluster.
Using Standby Continuous Replication, we can have a high available database copy on the remote site for disaster recovery and we have the option to specify lagged log reply time.

High Availability in Exchange Server 2010
Database Availability Group is a group of up to 16 servers that holds the set of replicated Mailbox databases and DAG is the boundary of replication and the failoverswitchover process among those mailbox databases.
High Availability concept of Exchange 2007 like LCR, CCR, SCC and SCR are not available in Exchange Server 2010. Exchange 2010 has a new high availability model name Database Availability Group. In actual LCR and SCC concepts has been completely removed but the concept CCR and SCR are combined and evolved into more unified High Availability Solution knows as Database Availability Group.

Using DAG, We can achieve redundancy at the server level, database level and the data resiliency. Below are the new component in Database Availability Group that manages the failovers

• Active manager is the primary component of Database Availability Group
• Exchange 2010 use AM to manage switch over and failovers, instead of the exchange cluster resource DLL and the associated cluster services used in the previous version of exchange
• Active Manager runs on all mailbox servers that are part of DAG member

New terms and functionality of Database Availability Group will be discussed in next topic

Installing Exchange Server 2010 on Windows Server 2012

I tried a lot to install Exchange Server 2010 on Windows Server 2012 RTM Operating System and end up in lot of errors. Also, I don’t find any information related to that error on Internet. Today I got the information from MS Exchange Team blog stating that Currently, Exchange Server 2010 Sp2 is not supported in Windows Server 2012 and they are working on this to make it possible.

 

Coming to conclusion, by today Exchange Server 2010 SP1 or SP2 can be installed only on Windows Server 2008 Sp2 and Windows Server 2008 R2 Sp1 and Exchange Server 2013 Preview can be installed on Windows Server 2008 R2 Sp1 and Windows Server 2012

5 Shell commands for daily use - Exchange 2007

Below 5 shell commands makes the exchange server administrator work quick and easier in administrating exchange server.

1. To check whether all exchange server related services are running normal?
Test-ServiceHealth or Test-ServiceHealth -Server ServerName

2. To check the Database Mount Status, backup status
Get-MailboxDatabase -Server ServerName -Status | FT Name, Mounted, backupinprogress, lastfullbackup, lastincrementalbackup

3. If High availability configured for Mailbox Server, to check the storage group and mailbox database opy status
Exchange Server 2007 CCR -> Get-StorageGroupCopyStatus -Server ServerName
Exchange Server 2007 SCR -> Get-StorageGroupCopyStatus -Identity MBSRV\SG1 -StandbyMachine Server2

4. To check the Mail queue status
Get-Queue -Server ServerName | FL

5. Testing Mailflow whether mail can be successfully sent from and delivered to the system mailbox on a computer that has the Mailbox server role installed
Test-Mailflow Server1 -TargetMailboxServer Server2
Test-Mailflow Server1 -TargetEmailAddress externalemailaddress
Inform if any details are needed.

Exchange Server 2007 Server Roles in short

Mailbox Server
Mailbox Server holds the Mailbox database and Public folder databases for your organization. It only retains the mailbox and it won’t transfer your mails. Transferring mails between your mailbox servers are handled by Hub Transport servers. The mailbox server role will be introduced only after the installation of Hub Transport Server and Client Access Server Roles. 4 types of high availability options are introduced in Exchange Server 2007, if we are installing Mailbox Server with the High AvailabilityClustering options Like CCR, SCC, or SCR, then no other server roles to be installed with this server role.

LCR – will provide an option to achieve HA at the database level and not at the server level. LCR specifically designed for small business organization, Active Mailbox Databases can be replicated to the passive Mailbox Database on the same server, if the active database goes down, we can activate the passive copy to function as active and if the server goes down, Mailboxes won’t be accessible until the server got rebuild and the mailbox got restored.

CCR – will provide an option to achieve HA at the database level and the server level. CCR will replicate the Active Mailbox Server from one server to Passive Mailbox Database at another Server, Where in, if the active Server goes down, automatic failover will occur and the passive server will function as active.

SCC – will provide HA at the server level only. if the active server goes down, the passive server will begging to function as active by referring the active copy which is accessible for all the servers in SCC. We can have centralized location to place the Mailbox and public folder database and the active server point to the same location. It’s like Clustering option available in Exchange Server 2003. If the SAN goes down, mailbox won’t be accessible.

SCR – will provide HA option at the Site level failure. With SCR there is no need to implement windows failover clustering feature installed to replicate the active database to passive database. Like active and passive mailbox database copy in other HA option, we have Source Database and Target Database in SCR.

Client Access Server
The role that handles client requests for OWA, Outlook Anywhere, ActiveSync, OVA and offline address book distribution. MAPI request from outlook client are directly connected to mailbox database, even though the MAPI clients are directly connected to Mailbox Database to access the mailboxes, MAPI client still depends on client Access Server for Auto Discover and Availability Service. CAS is responsible for any connection to Mailbox Server, when you want the Mailbox Server from outside the Exchange organization CAS is responsible. It’s also responsible for Non MAPI Clients connection.
This role must be installed after the hub transport role and before the mailbox server role. You can install the mailbox server role at the same time as the client access role, but not before.

Hub Transport Server
The Main Purpose of the Hub Transport Server Role is to transfer the mails throughout your exchange environment, this server role is responsible for internal mail flow, it replaces the bridge head servers in Exchange server 2003. This can be used as an edge transport server in Smaller Organization by installing and anti spam agents in Hub Transport Server itself. This must be the first role installed in Exchange 2007. You can install the client access server role and the mailbox server role at the same time as the hub transport role, but not before.

We have two connectors to look at in Hub Transport Server.

Send Connector – Responsible to outbound mail flow, by default, there is no Send Connector created (which means mail flow will not happen externally) to route external mails, we have to create a send connecter based on our requirement.

Receive Connector – Receive connector is responsible to receive inbound emails. By default the external mails are not received internally until the anonymous authentication is enabled

Unified Messaging Server
Functions as the interface point for the VOIP gateway or IP-PBX phone system. Allows user mailbox to be the single point of storage and access for voice mail and fax messages, in addition to their normal email.

Edge Transport Server
The Edge Transport Server Role is to transfer mails from inside of your organization to the outside world. It should be implemented at the edge of the network (perimeter Network). Main purpose is to prevent your exchange server from all kinds of Attack. Must have ports 25 (SMTP) and 50636 (LDAPS) open from it to the hub transport server on the internal LAN. Port 25 is to send mail in. Port 50636 is to replicate the Exchange information that it needs, such as changes to users’ safe and blocked senders lists.

Edge Synchronization –Since the Edge Transport Server is sitting at the edge of the network and to have to communication between the Hub Transport Server, we are having edge synchronization. It is the process to update the ADAM in the Edge Transport Server

Address Rewriting – Its additional feature which is used to rename the email address from internal users. This option will provide an uniformity in the SMTP address if we are having lot of domains and if company wish to have the external SMTP

How to Install Exchange Server 2007 – Short Note

In this article we are going to discuss about the perquisites plan to install Exchange Server 2007, Important topics on this page are

1. Prerequisites to install Exchange Server 2007
2. Exchange server 2007 Installation Types

Prerequisites to Install Exchange Server 2007

Before Installing Exchange Server 2007, we have to go through the Prerequisites to install Exchange Server 2007. First we will look into the preparation before installation

Preparation includes the following operations

1. Hardware Preparation
2. Permissions
3. Active Directory Preparation
4. Prepare Switches
5. Software Preparation and
6. Some Important Considerations

1. Hardware Preparation

• 64 bit Processor – should have 64 Bit Processor
• Memory – 1 GB recommended. Depends upon the Mailbox included in your Exchange Organization
• Hard disk Space – 1.2 GB for exchange and 200 Mega byte for system drives
• Formatted – NTFS

2. Permissions

User who is going to prepare AD should have permissions of

1. Schema Admin
2. Enterprise Admin

Active Directory Preparation

• Schema Master should be in windows 2003 with SP1
• 1 Global catalog server for each site
• ForestDomain functional level – Windows 2003

3. Prepare Switches

/prepare legacy exchange permissions – when we are having exchange 2000 or 2003 in our existing environment

/prepare schema – this will add various objects and attributes related to that object

/prepare AD – prepare the current domain and prepare a universal security group for the new exchange 2007 installation

/prepare domain “domain name”– only in the domain on the remote sites, or in the different domain

4. Software Preparations

1. OS – 64 bit of windows 2003, windows 2008
2. Microsoft Management Console 3.0 – By default included in windows 2003 server SP1
3. .Net Framework 2.0 with the hot fix. This should be installed before installing IIS
4. Power shell 1.0

5. Important Consideration

1. Raise your functional domain to Native mode
2. No exchange 5.5
3. Mailbox role – IIS, If you are installing Exchange Mailbox server IIS installation will be the prerequisites
4. Client Access – asp.net , and for Client Access Server Role asp.net should be enabled

Exchange server 2007 Installation Types

There are two types of installations in Exchange Server 2007,

• Typical Installation
• Custom Installation

1. Typical Installation

When we are performing the Typical Installation, the following server Roles will be automatically Selected, This typical installation is suitable for small Organization.

• Hub transport
• Client access
• Mail box server roles
• Exchange management console will be installed together

2. Custom Installation

If we plan to install the Exchange Server Roles in separate server to go for high availability solution we can go for this option

Following roles are the option for us to choose when we select the Custom Installation

• Hub Transport Server
• Client Access Server
• Mailbox Server
• Unified Messaging Server

The above four Server Roles can be installed together in single Server or in separate server

• Edge Transport Server – Should be install in the perimeter network
  • Exchange management Console – If we want to manage the server from windows XP , we can go for this option

We can also choose for active/passive clustered mailbox server