A Virsto One snapshot (vSnap) is a recorded state of a virtual disk (vDisk) at any given moment in time. vSnaps are immutable; they can be created and deleted but never modified. Due to the fact, vSnaps take up no additional disk space; they can be created very fast and easy, every minute, hour, whenever needed.

A snapshot is created by writing a special metadata marker (logmark) to the log device. The logmark contains a list of all vDisks included in the snapshot and other metadata information. A typical snapshot logmark is rather small (several KBs at most) and its insertion does not impose any measurable performance overhead. More than one vDisk can be snapshot at a time, i.e. a logmark may contain metadata for multiple vDisks. This provides for atomic transactional snapshots capability across multiple vDisks.