When I provision a lazy or eager zeroed, 1TB VM, both cause container storage … This KB describes how to convert a Lazy Zeroed disk to Eagerly on Vmware.

Step 1:Check where Vmware stored on ESX servers. With a lazy zeroed thick disk, a read returns only used blocks. You should check these steps to apply converting operation. Thin-provisioned disks are the best choice to save datastore space at the moment of disk creation. In general information you ‘ll get ESX Host name which vmware machine stored. Lazy zeroed thick-provision disks are good for their short creation times, but they do not provide as much speed as eager zeroed disks do, and are less secure. Thick provisioning can be accomplished by creating Eager Zero Thick VMDKs. Data remaining on the physical device is not erased during creation, but is zeroed out on demand at a later time on first write from the virtual machine.

When the OSR value is equal to 0, it is considered a thin disk and when it is set to 100, it is considered a thick disk.

performance of laze zeroed. vSAN Thin vs Thick Provisioning. Space required for the virtual disk is allocated when the disk is created. Thick Provision Lazy Zeroed.

Eager zero provisioning writes zeros to all allocated space when creating a virtual disk. Let’s start with how vSAN defines a thin or thick provisioned disk. Therefore, cloning would be out of the question as well. Thick Provision Lazy Zeroed Creates a virtual disk in a default thick format. I can't storage vMotion as no other datastores have enough space to accommodate 20TB of space. Thick Lazy Zeroed： 一次佔用所有空間 (All Space Allocated)，建立時間 較快，而未使用的 Block 空間 不會 預先進行 Zeroed 處理。 Thick Eager Ezroed： 一次佔用所有空間 (All Space Allocated)，建立時間 較慢，而未使用的 Block 空間 會 預先進行 Zeroed 處理。

Edit: This is a 40TB Thick VMDK that is attached to a Windows 2008 OS. Space required for the virtual disk is allocated when the virtual disk is created.

The main reason for this is that when the VMDK is thin, or lazy zero thick, the hypervisor will need to allocate that new block that is being written to and zero it out. First of all, this was indeed true with a lot of the older storage system architectures (non-VAAI). Data remaining on the physical device is not erased during creation, but is zeroed out on demand at a later time on first write from the virtual machine. On vSphere client click vmware machine and “summary”. When the disk is created it is not erased but zeroed out on demand while writing the data from the virtual machine. Creates a virtual disk in a default thick format. Windows is only using half of that so 20TB. Here is the disconnect. Eager Zero Thick VMDKs will automatically guarantee space reservations within NDFS.

Thick provision lazy zeroed :-Thick provision laze zeroed when used it allocates all the space from the datastore to the vm at time of creation only. Lazy zero thick disks provide better performance than thin disks, but worse than eager zero thick disks. Within a vSAN Storage Policy there is a setting called ‘Object Space Reservation’ (OSR). I've got 20TB of unallocated space within Windows that I'd like to reclaim.