What is a Snapshot?
- It is a point in time state of the virtual machine
- When you take a snapshot a delta disk gets created.
- If you create another snasphot another delta disk will be created
- The delta disk is mounted as ReadWrite (RW) whereas the original disk is mounted as ReadOnly (RO)
- This delta disk is thin priovisioned disk, and grows in chunks of 16MB
- After creation of Snapshot all disk writes within the VM go to the Snapshot-disk (delta disk) and not to the original disk (flat disk)
In vSphere, snapshots are based on “COW“
COW ==> Copy on Write Snapshots
In COW, all new writes always go to the delta disk.