Active backup destination: File
Media name: "incremental_exchange.bkf created 21/01/2010 at 3:55 PM"
Error: SERVER\Microsoft Information Store\First Storage Group is not a valid drive, or you do not have access.
This is a very obscure error message, and is almost impossible to decipher at face value. I spent many days trying to fix this error, and eventually discovered that you cannot create an incremental (or differential) backup when circular logging is enabled.
Turning off circular logging will enable an incremental backup to be created.
Another symptom encountered with this problem, was whenever I started an incremental backup it would continuously prompt me "Insert the following media: incremental_exchange.bkf created 21/01/2010 at 4:46pm Media #1. Do you want to continue?" When I clicked "Yes", it prompted me again. When I eventually clicked "No", the backup failed. The report showed the error message detailed above.
More information about circular logging:
How to disable circular logging:
Other similar threads:
How to create Exchange backups with NT Backup: