Sparse devices

• Make a writeable snapshot of an empty virtual device:

• lvcreate -L 100M --virtualsize 2T -s vg1

• First, this creates a virtual device full of 0s. All reads return blocks of 0s. All writes are discarded.

• Then it takes a snapshot of this and any data you write is stored inside this snapshot.

• Don't read what you didn't write.