Understanding the underlying mechanics of how Exchange Server works and how it stores messages can be very helpful to administrators especially when problems occur and resolution is needed immediately.

One of the most important components of the Exchange Server is that of the database which contains all the messages and directory information before those messages are applied to the database. Exchange Server 5.5 Standard Edition uses fault-tolerant, transaction-based databases that can grow to a maximum of 16 GB.  The size of the database for Enterprise Edition is limited only by the hardware used for storage. As with all databases Exchange Server uses transaction log files to be able to reconstruct the data should a failure occur. This data has already been accepted by the server but has not yet been committed.

The important database components of Exchange Server 5.5 include the Information Store and the JET Database Engine. The Information Store is actually comprised of two separate databases: the private information store database, Priv.edb, which manages data in user mailboxes and the public information store, Pub.edb, which manages data in public folders. Both databases are based on the JET format used to track and maintain information by utilizing the log files.

Administrators can encounter problems with the Exchange Server if any of these log files or the database become corrupted for some reason. Typical areas where database files can become corrupted include:

• Page (file system) level
• Database (JET database engine) level
• Application (Exchange information store) level

And the three most common errors that are associated with file-level problems in an Exchange database are:

• -1018 JET_errReadVerifyFailure
• -1019 JET_errPageNotInitialized
• -1022 JET_errDiskIO

Most of the -1019 and -1022 errors are caused by problems in the underlying system but the -1019 and -1022 errors can also be the result of errors in the Exchange Server code itself.

Continue reading Troubleshooting “–1018” Exchange Server Database Errors