I support a user running ShadowProtect Desktop 3.1 on Vista Ultimate SP1.  He has a typical Full/Incremental backup schedule where the first incremental is scheduled for 9 AM and the last for 6 PM.  Last night at around 11 PM, he removed the USB external drive holding the SP backups and brought it home.  He reconnected the same drive this morning well in advance of the 9 AM scheduled incremental.  However, at 9, instead of doing an incremental backup, SP did a differential.  The PC had been running continuously overnight, but with one reboot in between the 6 PM and 9 AM backups.  No crashes or anything out of the ordinary.

The user obviously wants to avoid having differential backups run while he's otherwise using the PC, so I'm trying to better understand what causes SP to run a differential instead of an incremental, and what settings will minimize the need for differential backups.

Thanks!

There are two reasons why a differential is taken instead of the Fast Incremental.  They are a dirty shutdown and/or missing incrementals.  You stated that the system rebooted over night, was it planned?  Is there event that precipated the reboot? 

We have had a few rare cases where shutdowns actually BSOD during the process but now one very notices because the system is set to auto reboot.  I would manually test this to see if the reboot is really clean or not.  Check the event logs for any messages related to dirty or bad shutdowns.  Also, check to see if you can manually force a fast incremental after a simple reboot.

If there was a missing backup file after the USB drive was plugged back in, then that could cause the issue as well.

Send us your log files for the time that the differential was taken and we should be able to quickly see why it was taken instead of a fast incremental.  You log  files can be found in c:\program files\storagecraft\shadowprotect\logs.

STC