[ TIP OF THE DAY ] Storage Space Reclamation for a vmdk file in ESXi.

 What is Storage Space Reclamation size of a thin provisioned vmdk file in ESXi? Thin provisioned disks are designed to expand and consume more disk space as the virtual machine requires. Unfortunately, thin VMDKs only expand. They don’t shrink on their own to release freed disk space. When we use thin provisioned vmdk, the size of the vmdk expands as we pile up data in the OS. 

But if we delete some data from OS, the reclaimed space in the OS will not be reclaimed from the vmdk. It will continue to occupy the maximum space it have ever used after creation. When you create a VMFS6 datastore, you can modify the default parameters for automatic space reclamation. After you enable space reclamation, the VMFS6 datastore can start releasing the blocks of unused space only when it has at least one open file. This condition can be done when, for example, you power on one of the VMs on the datastore.