Section 20.5. Restore

20.5. Restore

This entire backup is pretty useless unless you can restore after a meltdown. This section will help you in that arena.

20.5.1. Repair or Restore?

One of the first questions you'll need to ask yourself after a disaster is if it is worthwhile to try to repair the existing Exchange Server or restore from backup. New tools and technologies make repairing much easier than in previous versions, especially at the individual mailbox level.

20.5.2. Common Tasks for Repair or Restore

Repairing and restoring have some tasks in common. For example, before you jump in and start looking at Exchange, make sure your foundation is solid. In this case, your foundation is the Windows Server on which your Exchange Server resides. Running a few simple verification exercises can save you hours down the road. Many times I have seen administrators spend hours repairing or restoring their Exchange Server, proudly receiving kudos and accolades from their coworkers, only to see the server crash and burn soon afterward because the foundation wasn't solid.

The first thing to do before you start repairing or restoring is to ensure the server on which Exchange is running is operating correctly. This includes things such as:

Hard disk media check

Use chkdsk or some other utility provided by your disk vendor to verify the integrity of the actual media.

Windows Server file verification

Use chkdsk to verify the filesystem and the filesystem metadata.

Last known good configuration

When booting Windows, try selecting the last known good configuration.

Windows Recovery console

This option is available in Windows Server 2000 and beyond and is accessed when booting from the operating system CD.

Restoring with backup sets

Restoring with backup sets is, of course, always an option. However, it can be quite tedious and take a significant amount of time. This method entails first building a replacement server and then restoring previous backup sets to create a functioning server.

Automated System Recovery (ASR)

ASR provides a convenient and automated way to restore your Windows 2003 server. Using the ASR backup floppy in conjunction with booting from the Windows Server 2003 CD, you can fully restore your server to its last ASR backup state.

Obvious problems

While it may seem trivial, ensure that Exchange hasn't shut itself down due to the disk filling up and running out of space.

20.5.3. Exchange Repair

After you've ensured that your Windows server isn't the problem, or if it was, that you've now repaired it, it's time to move on to the Exchange Server. Recall those two possibilities: repair the existing installation or restore from backup. Whichever option you choose, back up the server first, no matter what state it is in. This ensures that if your repair or restore efforts are unsuccessful, you at least have the latest point-in-time backup, even if it is corrupt. If things become so fouled up trying to restore or repair, at least you know you can get back to where you were right after the failure.

20.5.3.1. Repairing Exchange databases

Included with Exchange are several command-line tools that can help you repair corrupted or damaged database files and message stores. In a 2003 standard installation, these tools are found in C:\Program Files\Exchsrvr\bin (substitute the appropriate drive letter and path depending on your particular installation). ESEUtil is a tool that can check the integrity of your database or repair a damaged one. The ISINTEG tool tests an offline store for integrity errors and can also repair those errors. In 2000, ISINTEG is found in C:\Program Files\Exchsrvr\bin, and ESEUtil is located on the Exchange 2000 CD in the D:\Support\Utils folder and must be installed (where D: is the appropriate drive letter for your CD drive).

These are very powerful tools and offer a great deal of flexibility and options to help restore or recover an Exchange database. In fact, in some instances the only options for recovery or repair are these command-line utilities. More information about these tools can be found online at http://support.microsoft.com by entering either eseutil or isinteg as the search term.

20.5.3.2. Repairing by reinstalling

One option for getting your failed Exchange Server operational is to reinstall on top of an existing installation. This generally works for instances in which some of the executables or DLLs necessary for Exchange to function have become corrupt or were accidentally deleted, or in which registry entries have become corrupt.

Of course, if you are taking this route, the Exchange Server processes are shut down during the reinstall and inaccessible to users. And it is important to remember that you must bring any software you install to the same patch level that was installed when the backup was created.

If you choose this method, use the /DisasterRecovery switch to tell the installer not to make changes to Active Directory. This keeps the installer from registering a new Exchange Server in Active Directory. Keep in mind that the Exchange Server configuration must still be in Active Directory. If you manually deleted the information from Active Directory (or the server has been down so long that it has been purged), you'll need to take extra steps in order to repair.