After installing Exchange Sp2 you must make the following changes to the Registry

1.          On the computer running Exchange Server, start\Run\Regedit

2.          Open one of the following registry keys:

3.          The registry entries have to be made on each individual Store.  (Private and Public)

****Please confirm the drive space on the server within the partition that the exchange databases are loaded. ******

To configure the database size limit on a mailbox store, open the following registry key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\Server name\Private-Mailbox Store GUID

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\Server Name\Public-Public Store GUID

4.          Right click on the Private Store GUID and select New -> Dword Value

5.          For the value name type: Database Size limit in GB.

6.          Double -click the Database Size limit in GB and set the value.  But default after installing Exchange sp2 it increases to 18Gb.   Type any value between 1 and

75. These numbers represent 1GB to 75GB

7.          If you want to increase the size of the Public Store follow steps 4 – 6 above.

8.          Restart the Information Store

9.          Look in the Application Log within the Event Viewer 1216 this file should show the database size of 25GB or the desired size.

After you Finish with the Offline Defrag,
Clear all the log files from C Drive, C Drive MDBDATA Folder should be empty. On M Drive MDBDATA Folder you should see only Priv.edb and Pub.edb

Start the Information Store Service, Incase if it gives you the error -1011, then ONLY you need to run this command below,

M:\exchsrvr\bin>isinteg -patch

Start the Information Store Service, Service will get Started.
Run the Performance Optimizer and move the Information Log File Location to M Drive.
So the DB Log Path and DB Database Path will be on the Same Drive, that is M Drive.

Now, Go-ahead and Start the Other Service MTA and IMS Service {All the Exchange Related Services}
Check for the Internal and External Mail Flow.