Properties Of Snapshots

• The first property of a snapshot, is the amount of disk space it was given. If we run out of disk space (too much of the original volume changed), the kernel will drop the snapshot.
• The size of a snapshot may be increased while it is mounted. No need for file-system resizing tricks here.
• A snapshot may be read-only or read-write. If it is read-write, then the snapshot's disk space is also used for writing on top of the snapshot.
• When creating a snapshot, we may define the chunk size (i.e. how much data to COW when there is a change in the original volume). A larger chunk means better throughput, but possibly higher latency, and more waste of disk space.
• We may stack snapshots together (everything in LVM2 is stackable). The performance of reads might degrade.

Originally written by guy keren