When backing up SQL databases using the incremental option the backup job fails with “The statement BACKUP LOG is not allowed while the recovery model is SIMPLE” This is because the recovery model of the database being backed up is currently set to “Simple”. To resolve this error you must either change the database backup type to full, or change the database recovery model in SQL to either “BulkLogged or Full”.
The new EMC Avamar 6.1 Microsoft SQL plugin feature actually detects the recovery model of the database and skips the incremental backup, places a message in the log and automatically promotes the backup from an incremental to a full backup. So you can also upgrade Avamar to version 6.1 to resolve this error as well.