vSphere Snapshot Basics – Part 1

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.

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