You should not configure Microsoft Exchange Server 2010 databases to use circular logging if you also plan to use the Volume Shadow Copy Service (VSS) to enable third-party (or custom) backup and recovery operations. If circular logging is enabled, the following will be true:
You cannot restore the individual databases if circular logging was enabled during the backup operation or is enabled during the recovery operation.
You can delete transaction logs in the same directory when a database is restored, although those logs might be part of a different Exchange 2010 database. This means that if circular logging is enabled, only point-in-time recovery operations are possible.
You cannot perform incremental or differential backup operations.
Local continuous replication (LCR) and cluster continuous replication (CCR) are included in Microsoft Exchange Server 2007, but these features are not available in Exchange 2010. Circular logging is not supported in LCR and CCR configurations in Exchange 2007.