Explanation
When a snapshot is created, a bitmap and blockmap are created in the metadata of the snapshot FS. The bitmap
is used to keep track of blocks that are changed on the production FS after the snapshot creation. The
blockmap is used to indicate the exact address from which the data is to be read when the data is accessed
from the snapshot FS.

Explanation
It is a recurring unavailability that is characterized by an outage, then availability again, then another outage,
and so on