Introducing a new snapshots mechanism

InfiniBox release 3.0 introduces an improved snapshot mechanism. This mechanism replaces the snapshot - clone dualism with a single entity that can become writable.

Transferring old snapshots to the new mechanism

InfiniBox systems with software versions lower than 3.0 are transparently upgraded to the new snapshot mechanism.

• A snapshot leaf on the volume tree remains a snapshot
• A clone leaf on the volume tree turns into a snapshot

Restoring a volume from a snapshot

A volume can be restored from any of the snapshots down the volume tree.

Increased space efficiency

The new snapshots mechanism requires less writes and saves more space. Consider the following example.

1. Create a volume and create a snapshot of this volume
   • The snapshot references to block A of the volume
      
2. Write to the volume
   • Block A is replaced with block A' 
   • The snapshot writes the capacity of block A as it is no longer available on the volume
     
3. Write to the snapshot - to the same block
   • The snapshot does not point at blocks A or A' as these blocks are replaced with block A''
   • The space of block A - as it is no longer needed - is reclaimed