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SnapBack OEM

VSS Alternative

Microsoft’s Volume Shadow Services (VSS) provide backup application developers the ability to effectively freeze a view of a disk drive at a point in time so a backup can be taken without the issues of rapidly changing and open files. This has minimal effect on the overall loading of the disk drives and processor during the backup process.

VSS are only available within the Windows Vista and beyond family of operating systems. Adoption of this family of operating systems has not been as rapid or as complete as expected, consequently backup application developers have clients who still have substantial numbers of Windows 2000 and Windows XP based computers. Vendors wish to provide support to this part of the market.

SnapBack have made available the tried and tested technology from the SnapBack products which is comparable to VSS, providing similar services across the entire range of Microsoft Operating systems.

The sbotman driver provides the ability to effectively freeze a disk drive’s image in time. This is achieved by intercepting all disk drive write instructions and creating copies of the original drive sectors before allowing the write to complete. The interface to the sbotman driver provides functions to initiate the start of the freeze, manage the storage of saved drive sectors and return copies of the saved sectors.

sbotman is designed to be failsafe. As the driver copies the original of all sectors to be changed before allowing a change to be written to disk, a failure of the driver will not cause corruption to the disk. Failure modes are handled with a graceful degradation. These primarily consist of conditions where resources allocated to the driver have proved insufficient. For example if the cached disk area is insufficient to store all the writes, the driver will halt the write monitoring and report the failure to the next call to the driver.

The driver is designed to support a simple raw drive backup. This is where the whole of a drive (or partition) is backed up in sector order. Blocks of the raw drive are read, these are then compared with the drivers cache of recorded original sectors and updated. The driver releases resources that are no longer required as the backup proceeds. A pointer to the current point of the backup is communicated to the driver so that it only records changes to sectors that have yet to be backed up.

Further technical documentation on the API

The OEM program makes available to you:

For further information and to discuss licencing, please contact us