In Isilon OneFS, what is a characteristic of CoW with snapshots?
A. Used for small changes, inodes, and directories.
B. Avoids the double write penalty.
C. Increases file fragmentation.
D. Used for more substantial changes such as deletes.
With copy on write, as the name suggests, a new write to HEAD results in the old blocks being copied out to the snapshot version first.
Although this incurs a double write penalty, it results in less fragmentation of the HEAD file, which is better for cache prefetch, etc.
Typically, CoW is most prevalent in OneFS and is primarily used for small changes, inodes and directories.