Thank you for your interest in Acronis Disk Backup Software
Here is a description of the unique Acronis Snapshot technology:
Once Acronis True Image initializes the backup process of a volume (which logically corresponds to a single partition, if there are no Dynamic Disks), Acronis Snapshot Manager flushes the file system mounted to that volume temporarily freezing all the operations on the system volume. Immediately thereafter, the Snapshot Manager driver creates a point-in-time view of the system volume and a bitmap describing the used sectors on this volume. Once the bitmap is created, the filter driver unfreezes the I/O operations on the system volume. It generally takes only several seconds to create a point-in-time view of the volume. After that, the operating system continues working as the imaging process is under way.
Acronis True Image reads the sectors on the system volume according to the created bitmap. Once a sector is read, the appropriate bit in the bitmap is reset. In its turn, the Acronis driver continues working to hold the point-in-time view of the system volume. Whenever the driver sees a writing operation directed at the system volume, it checks whether these sectors are already backed-up, if they are not, the driver saves the data to the sectors that will be overwritten to a special buffer created by the software, then it allows the sectors to be overwritten. Acronis True Image backs up the sectors from the special buffer, so that all the sectors of the point-in-time view of the system volume will be backed up intact. Meanwhile, the operating system continues working and the user will not notice anything unusual in the operating system functionality.
If we are talking about complex applications such as databases please read the following FAQ article: