One helpful aspect of Microsoft Exchange Server 2007's continuous replication feature is that it creates a secondary database copy. This tip explains the steps involved in performing a continuous replication integrity test, including how to suspend the continuous replication process, perform an integrity check and test your log file integrity.
Generally, continuous replication works very well. However, external factors can cause a log file or database corruption on the passive node. Because the passive node is designed to help you to recover from a disaster, it's a good idea to test it occasionally to ensure that no corruption is present.
Note: Before you can perform any sort of test against the passive database and its log files, I suggest suspending the continuous replication process.
To suspend continuous replication, open the Exchange Management Console (EMC) and select the storage group that you want to test. Next, click the Suspend Continuous Replication link found in the Actions pane. Exchange then will display a dialog box asking if you really want to suspend continuous replication. This box also lets you enter some text explaining why you are suspending continuous replication.
You can also suspend the continuous replication process using the Exchange Management Shell's Suspend-StorageGroupCopy command. This command requires two separate switches.
The first is the Identity switch. You can use this switch to specify the name of the storage group. The second switch is SuspendComment, which provides a comment regarding why continuous replication was suspended. Here is what the command looks like in action:
Suspend-StorageGroupCopy –Identity "First Storage Group" –SuspendComment "Continuous Replication was suspended by the Administrator for the purpose of performing an integrity check on the passive database.
After suspending the database, you can perform an integrity check. First, I recommend checking log files associated with the passive database. But you'll need to know the log file prefix for the storage group before you test the files.
To obtain the log file prefix, open the Exchange Management Console and navigate through the console tree to: Server Configuration -> Mailbox. Select your mailbox server and then select the storage group you want to use. Right-click on the storage group and choose Properties from the menu. The resulting property sheet will display the log file prefix.
Once you know the log file prefix, you must determine the location of both the log files and system files that the passive database copy uses. You can retrieve this information from the current property sheet by going to the Continuous Replication tab and noting both the log file location and the system file location.
To test the integrity of your log files, open the Exchange Management Shell and enter the ESEUTIL command with the K switch, followed by the log file location and the log file prefix.
For example, suppose that the passive copy of the log files reside in the Q:\Mailbox\LocalCopies\First Storage Group folder, and had a log file prefix of E00. In such a case, the ESEUTIL command would look like this:
ESEUTIL /K "Q:\Mailbox\LocalCopies\First Storage Group\E00"
Exchange Server 2007 will now verify your log files. This process can take anywhere from a few seconds to several hours, depending on how many log files are present. Assuming that no errors are encountered, you can begin verifying the integrity of the database.
Note: Microsoft offers an easy to follow TechNet article that explains step-by-step how to verify an SCR copy.
About the author: Brien M. Posey, MCSE, is a five-time recipient of Microsoft's Most Valuable Professional (MVP) award for his work with Exchange Server, Windows Server, Internet Information Services (IIS), and File Systems and Storage. Brien has served as CIO for a nationwide chain of hospitals and was once responsible for the Department of Information Management at Fort Knox. As a freelance technical writer, Brien has written for Microsoft, TechTarget, CNET, ZDNet, MSD2D, Relevant Technologies and other technology companies. You can visit Brien's personal website at www.brienposey.com.
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