We've been talking about Snapshots and I find that they are sometimes misunderstood.
I always use VMware's best practices when I use them, and also when I talk about them.
Do not use snapshots as backups.
The snapshot file is only a change log of the original virtual disk, it creates a place holder disk, virtual_machine-00000x-delta.vmdk,
to store data changes since the time the snapshot was created. If the
base disks are deleted, the snapshot files are not sufficient to restore
a virtual machine.
Also if a VM is reverted back to a previous state, all files are restored to a previous state, we can't brick level individual files, also a lot of applications such as Microsoft Exchange server do not support Snapshots/Checkpoints (Hyper-V).
Maximum of 32 snapshots are supported in a chain. However, for a better performance use only 2 to 3 snapshots.
The more snapshots per VM, the more storage we require and potentially each Snapshot could grow to the size of the -Flat.vmdk, also we are potentially taking a snapshot of the Memory state of the VM.
This then introduces multiple Read points per file, so there could be a performance hit.
Do not use a single snapshot for more than 72 hours.
The snapshot file continues to grow in size when it is retained for a
longer period. This can cause the snapshot storage location to run out
of space and impact the system performance.
When using a third-party backup software, ensure that snapshots are deleted after a successful backup.
Snapshots taken by third party software (through API) may not appear in
the Snapshot Manager. Routinely check for snapshots through the
Snapshot Manager fails to detect snapshots of VMs (1026380)
For more information and additional knowledge base articles visit the:
Best practices for using snapshots in the vSphere environment (1025279)