What you will learn in this tip: Microsoft Exchange Server backup can be extremely challenging when you have multiple versions of Exchange to back up. Luckily there are some things you can do to alleviate the problems that occur when you're backing up multiple versions.
Anyone who has migrated from Microsoft Exchange Server 2003 to either Exchange Server 2007 or Exchange Server 2010 has found out that Microsoft doesn't allow in-place upgrades. Instead, administrators are forced to deploy the new Exchange Servers within their existing Exchange environment and then migrate content from the old servers to the new ones.
If you work through a Microsoft Exchange Server migration like this, you will have a period of time when there are multiple versions of Exchange Server present on the network. For some, the coexistence period lasts only a few hours, but others may have to live with multiple versions coexisting for an extended period of time. It's also common for organizations that need to add additional mailbox capacity to invest in the latest version of Exchange even if other mailbox servers continue to run a legacy version.
Microsoft's approach for backing up different versions of Exchange
Although Microsoft has designed Exchange 2003, 2007 and 2010 to coexist within a common Exchange organization, coexistence can wreak havoc on your backups unless you do some planning up front.
There are a couple of different reasons why Exchange Server coexistence can have such an impact on your nightly backups, but all of the reasons boil down to the simple fact that although every version of Exchange Server uses an Extensible Storage Engine database, the database architecture is different in each version of Exchange.
These architectural differences are apparent when you examine Microsoft's recommended approach for backing up each version of Exchange. From Exchange 4.0 (the very first version of Exchange) through Exchange 2000, Microsoft only supported streaming backups (although there were some third-party utilities that used unsupported brick-level backups). In Exchange 2003 however, Microsoft introduced Volume Shadow Copy Service (VSS) backups. Even so, VSS wasn't quite ready for prime time and most organizations continued to use streaming backups.
In Exchange 2007, Microsoft did a lot of work to make VSS more palatable, and began to downplay streaming backups. Microsoft completely dropped support for streaming backups from Exchange Server 2010, and now VSS is the only supported backup method.
At first glance it would seem that it's possible for organizations running Exchange 2003 and Exchange 2007 to perform either streaming or VSS backups, and organizations running any combination of Exchange 2003, 2007, and 2010 servers can run VSS backups. While this concept holds true, it's important to remember that because the database architecture has changed from one version of Exchange to the next, so have the APIs used in backing up the Exchange Server databases.
For example, suppose you have Exchange Server 2003 installed in your organization and then you add an Exchange 2007 mailbox server. You can't automatically assume that your backup software will be able to back up the new mailbox server. In fact, you will only be able to use your backup software if you happen to have an Exchange 2007 backup agent (or other Exchange 2007 support).
Keep in mind that all of the major backup vendors offer multi-version Exchange backup capabilities. But also remember that these capabilities usually come at a cost. At the very least you will have to purchase an additional license for your backup software before you will be able to back up the new mailbox server. In some cases though, you may have to buy a completely new version of the backup software in order to gain support for newer versions of Microsoft Exchange Server.
Multi-version Microsoft Exchange Server backups
Performing multi-version backups isn't always as simple as upgrading your backup software or purchasing an additional backup agent. Depending on what backup software you are using, backing up multiple versions of Exchange can be a major ordeal.
For example, I back up my own network using Microsoft's System Center Data Protection Manager 2007 (DPM 2007). Even though DPM 2007 performs VSS backups, backing up the data alone isn't enough. Once the data has been backed up, DPM 2007 must use Exchange Server's ESEUTIL.EXE and ESE.DLL files to put the backup data into a consistent state. The instructions for DPM 2007 tell you to copy these files off of your Exchange Server and onto the DPM 2007 server. However, the contents of these files change from one version of Exchange to the next. Even installing an Exchange service pack invalidates the ESEUTIL.EXE and ESE.DLL files. This is because DPM depends on two files that must be copied from an Exchange Server. Even though the filenames remain the same, the files themselves change from one version of Exchange to the next. The files even change from one service pack to the next. Therefore, the files that you copy to the DPM server must exactly match the files that are in use on your Exchange server at that given moment.
Since the ESEUTIL.EXE and ESE.DLL files are version specific, several problems can occur if you attempt to back up multiple versions of Exchange Server. Fortunately, there are three ways to avoid this.
1. Keep everything consistent. Use the same version of Exchange on all of your mailbox servers and apply service packs consistently across the board.
2. Use the latest version of the ESEUTIL.EXE and ESE.DLL files. According to several sources on the Internet, the version of these files that's included with Exchange Server 2007 is backward-compatible with Exchange 2003. Having said that, I've never been able to successfully back up my Exchange 2003 servers using the ESEUTIL.EXE and ESE.DLL files from Exchange 2007.
3. Leave the ESEUTIL.EXE and ESE.DLL files off of your DPM 2007 server and allow ESEUTIL to run locally on each Exchange Server. This approach guarantees that you won't have to deal with version conflicts, but it can heavily impact the performance of your mailbox servers.
As you can see, complications can occur when backing up multiple versions of Exchange. In many cases these complications are easy to resolve, but it's worth spending some time figuring out exactly how your backups will have to change to accommodate a new version of Exchange Server before you deploy a new Exchange Server.
About the author: Brien M. Posey, MCSE, has previously received Microsoft's MVP award for Exchange Server, Windows Server and Internet Information Server (IIS). Brien has served as CIO for a nationwide chain of hospitals and was once responsible for the Department of Information Management at Fort Knox. You can visit Brien's personal website at www.brienposey.com.