Date: April 2011
Product & Version: NetVault
OS Version: Windows 2003 R2
Module & Version: Exchange APM 4.5.6
Symptoms: Exchange backup will hang checking the database state.
The event log of the Exchange Server shows the following error message:
MSExchangeIS (2156) SG1: Online defragmentation of database 'F:\SG1\PXP\PXP.edb' terminated prematurely after encountering unexpected error -1018.
The next time online defragmentation is started on this database, it will resume from the point of interruption.
The issue turned out to be that the exchange database was corrupted.