Snapshot can be nightmare for vmware administrator

Snapshot is the one of best feature of VMware. It is not backup solution but a good option if want to preserve some existing configuration/settings of vm/installed applications. User can take snapshot of vm and make changes if anything goes wrong, roll-back those changes with snapshot, taken prior making  changes. Most of the people uses this as backup and left it as for long time after creation. So, question here is how can be leaving snapshot becomes headache for Administrators.

As you guys are aware, when we create snapshot of vm a delta vmdk disk created and attached with vm. Original vmdk marked as readonly and all changes will be performed at delta vmdk. As Type of delta vmdk disk is thin and can grow upto the size of configured vmdk.

Example:
Size of datastore = 50 GB
Size of vmdk = 30 GB
Size of delta vmdk few MB but can grow upto 30 GB.

Now, suppose vmdk is Thick which already consumed 30 GB space of datastore and delta vmdk can grow up to 30 GB so, total space requirement would be 60 + GB.
Most of the peoples follow 10% threshold of free space. While snapshot created, admin was having enough free space 15GB but if anyhow, vm found as high IOPs, it will easily consume free space and create outage.

If type of vmdk is thin, even outage can't be avoided but can give us more time to full space of datastore.

As a good practice, we should delete snapshot once requirement of its completed.

As a work around, we can also create alert for snapshot usage. If snapshot reaches to configured alert value, alert will be generated and remediate action can be taken.

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