I have been looking at an old problem with VSS backups and SQL Server.
Consider this scenario:
You have a SQL Server backup strategy with normal (non VSS) full and differential backups.
Now you do a VSS backup of a file that is located on the same drive as one of your databases.
ntbackup backup "C:\test.txt" /f "D:\test.bkf"
You can see this in the error log:
I/O is frozen on database test. No user action is required. However, if I/O is not resumed promptly, you could cancel the backup.
I/O was resumed on database test. No user action is required.
Now you try to perform a normal (non VSS) differential backup of this database. The differential backup fails.
Msg 3035, Level 16, State 1, Line 3
Cannot perform a differential backup for database "test", because a current database backup does not exist. Perform a full database backup by reissuing BACKUP DATABASE, omitting the WITH DIFFERENTIAL option.
Msg 3013, Level 16, State 1, Line 3
BACKUP DATABASE is terminating abnormally.
There is a kb article about this issue.
http://support.microsoft.com/kb/951288
I have checked that this is a problem with SQL Server 2008 R2, even though the article only talks about SQL Server 2005.
Does anyone know if this is a bug or by design?
Ola Hallengren
http://ola.hallengren.com