What type of storage are you using? eg iscsi,SAN, NAS/NFS?
If using NFS it may be down to the way the filer is configured - from a similar thread relating to this
Question: What type of Disk Provisioning is supported in ESX?
Answer: Disk Provisioning:
- thick
- A thick disk has all space allocated at creation time. This space may contain stale data as it exists on the physical media.
- thin
- Space required for thin-provisioned virtual disk is allocated and zeroed on demand as opposed to upon creation.
Question: Why is Disk Provisioning different for NFS vs VMFS volume?
Answer: On the client side we have no control over how the server is going to allocate blocks for a file.
Question: What is the factor on NFS Server that causes it to be Thin or Thick provisioned?
Answer: It depends on how the filer is configured, but on almost all the filers we know of - the files will be thin provisioned.
Question:Why isn't there a common default standard?
Answer: Block allocation is not part of the NFS spec since NFS is a file level protocol. All servers will allocate blocks on demand (thin provision) but some can be configured to pre-allocate space for files based on the size of the file.
Question:Assuming that NFS Server has Thick provisioning by default will I be able to do Thin provisioning of vms?
Answer: No.
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