Microsoft's Exchange Disaster Recovery Analyzer (ExDRA 1.0) is a tool to inspect Exchange database files and log files. Basically, you point the tool to your Exchange server, you select (dismounted) databases and the tool starts to do its work.

Under the hood, the tools inspects the headers of database files and log files and uses that information to present you with a list of possible errors.

Of course, you can also get this information with eseutil.exe (normally in c:\program files\exchsrvr\bin).

To examine the header of a dismounted database, you can use eseutil /mh <path_to_edb_file>. From the header, you can read the shutdown state. During a disaster recovery, it will be in Dirty Shutdown mode. Under that line, you will see the logs that are required during the soft recovery process. From the header, you can also read the database signature, the log signatures and so on. But then you are on your own because you need to be able to interpret the data. That's always tricky!

So basically, ExDRA 1.0 gets the same information as eseutil.exe but automatically makes some conclusions depending on the output. It can certainly help during a disaster recovery because of the "level of stress" that can be involved.  

For an overview of how the tool works and some screenshots: Overview and screenshots