Hardware failures are one of the most prevalent and longstanding issues for all Exchange users. Even a single faulty hardware component on your disk storage subsystem may eventually lead to significant loss of Exchange Server data. Initially, these problems appear to be transient in nature, but may become worse progressively. In these situations, logical structure of your database is damaged. A typical example of such case is Event ID 447 being logged to the Application log of Windows Event Viewer as follows:

Event ID: 447
Description: Information Store (nnnn) A bad page link (error -338) has been detected in a
B-Tree (ObjectId: 70950, PgnoRoot: 157120) of database e:\Program
Files\exchsrvr\mdbdata\priv1.edb (157120 => 296404, 296403).

The Event ID 447 or error -338 may occur in any of the following scenarios:

A wise approach to remedy this problem is to restore your database from an online backup. If there is no valid database backup, you should try to perform database repair using the given steps:

If the aforementioned procedure fails to repair the Exchange databases, use Stellar Repair for Exchange Tool. The software provides myriad easy-to-use options to repair and restore your damaged Exchange databases. It safely recovers mailboxes from corrupt Exchange database (.EDB) files and restores them as Outlook PST files in your system. With the help of this advanced utility, you can recover Unicode-formatted EDB files.