In some cases I had problems with virtual machines and VSS based backup software. These problems are twofold;
- VSS based backups software executing a BACKUP LOG TO DISK = 'NUL' after taking a snapshot and thus invalidating the log chain.
- VSS based backup software taking full backups under the hood (thus resetting the base for differential backups)
For the first issue, I found the culprit; Veeam (http://www.veeam.com/vmware-backup/help-center/hyperv/index.html?transaction_truncation.html; http://www.veeam.com/vmware-backup/help-center/vsphere/index.html?transaction_truncation.html). To avoid this problem, I would like to have an option (under sp_configure) to disallow log backups to disk = 'NUL'
For the second issue, a seperate connect item exits: "Option to force VSS backup to copy_only" https://connect.microsoft.com/SQLServer/feedback/details/790560