Most Exchange Server environments will grow beyond their original sizing.  Sometimes this growth has been accounted for in the design, and sometimes it is not.  In either case the question to ask as the user base increases is whether to scale up or scale out.

What do each of those terms mean?  An example of scaling up would be increasing the capacity of a server to handle higher loads.  An example of scaling out would be adding new servers to spread the higher load across more hosts.

Each approach has its pros and cons in the context of the different Exchange Server roles.  In this post I’ll discuss the Exchange Server 2007 Transport server roles and the different scaling considerations that they have.

Edge Transport/Hub Transport Servers

The role of the Edge Transport server is to route incoming and outgoing internet email while applying security and compliance rules to messages.  The role of the Hub Transport is basically the same though it is also responsible for routing emails between internal mailboxes as well.

The Transport Server workload relies primarily on fast CPUs to assess and process each email message against these rules, and fast disks for reading and writing messages to the transport queue.

Processor Scaling

Scaling up with more CPU cores to handle higher workloads is appropriate; however, there is a practical limit of 4 CPU cores per Edge Transport server and 8 cores per Hub Transport server.  This is an obvious “scale out” threshold for this server role – if the server is already at the maximum number of cores and CPU is showing signs of a performance bottleneck then it is time to look at scaling out to more Transport servers.

Disk Scaling

Disk performance is slightly different.  Each Transport server has a transport queue, which is a location on the disk in which emails are read and written in a database.  Emails are only temporarily stored in this queue, and large capacity disks are quite cheap and common in servers these days, so disk space is not likely to be a problem for the volume hosting the transport queue. Continue reading Scaling Up vs Scaling Out Exchange Server 2007 Roles Part 1 – Transport Servers

Exchange Server 2007 introduced new terminology for describing the domain names that it will accept email for, and what it will do with that email.  This is referred to in Exchange Server 2007 as Accepted Domains.

In Microsoft’s own words, “an accepted domain is any Simple Mail Transfer Protocol (SMTP) namespace for which a Microsoft Exchange organization sends or receives e-mail.”

Accepted Domains fall into one of 3 categories – Authoritative, Internal Relay, and External Relay.  Any given namespace that is an Accepted Domain can be only one of those three types.

Authoritative Domains

Authoritative Domains are those for which an Exchange organization hosts mailboxes that have email addresses that use that domain.

For example, a company named Contoso Pty Ltd may own the domain name contoso.com and use email addresses of name@contoso.com.  The Exchange organization would be configured to consider contoso.com an Authoritative Domain.

An organization can have more than one Authoritative Domain configured.  Using Contoso Pty Ltd as an example again, they may have a second brand name of Contoso Services and use the contososervices.com domain name in marketing materials.  In this case the Exchange organization would be configured with both contoso.com and contososervices.com as Authoritative Domains.

Internal Relay Domains

Internal Relay domains are those for which an Exchange organization hosts some, but not all of the mailboxes that use that domain.  This scenario is sometimes also referred to as a “shared SMTP namespace”.

Internal Relay domains are common when two companies have merged but are yet to consolidate their Exchange environment into a single organization.  When they have a need for consistent email addressing across both Exchange environments Internal Relay domains are the solution. Continue reading Understanding Exchange Server Accepted Domains

In Part 1 of this series I discussed backup and recovery for each of the Exchange Server 2007 server roles and associated systems such as Active Directory.  In Part 2 I then described the process of backing up and recovering a Mailbox Server from the loss of a mailbox database.  In this part of the series I will demonstrate backup and recovery of the Hub Transport Server and Edge Transport Server roles.

Backing up Transport Servers

Unlike Mailbox Servers, the Hub Transport and Edge Transport roles do not require any special Exchange-aware backup software.  All of the necessary data for recovering a Transport server is contained within:

• Active Directory (for Hub Transport servers, but not Edge Transport servers)
• The Active Directory Application Mode (ADAM) database (for Edge Transport servers)
• The server’s file system
• The server’s System State

Hub Transport servers can be backed up using the built in Backup utility in Windows Server.  At the very least the backup should include the System State and the C:\Program Files\Microsoft\Exchange Server\TransportRoles location of the file system (and all sub directories).

Edge Transport servers are backed up in the same way as Hub Transport servers except for the Exchange Server configuration.  Because this is stored in ADAM it must first be cloned using the Export-EdgeConfig.ps1 script located in C:\Program Files\Microsoft\Exchange Server\Scripts.  Execute the script with the name of the file you wish to export to. Note this is a single command run on one line in the Exchange Management Shell.

export-edgeconfig.ps1 c:\edgeconfig.xml
 -key "abcdefghijklmnop"

It is recommended to either include this config file in your Edge Transport backups or use a path that is a shared folder on a remote server.

Recovering Hub Transport Servers

In this scenario the EXCHHUB server has been lost due to hardware failure.  Spare server hardware has been used to reinstall Windows Server 2003 along with the Exchange Server 2007 pre-requisites.  The newly built server has the same name and IP address of EXCHHUB.  Now we can begin the recovery of the Hub Transport server.
Continue reading Exchange Server 2007 Backup and Recovery Part 3 – Transport Servers