VMware - VMDK file - Thick vs Thin Provisioning - Size/Compressed

Hello @Tommy 

Thin provisioning is more space efficient, as it only allocates the amount of data written, while thick provisioning allots the entire capacity. Having said that, I think performance-wise, thick provisioning is better as it eliminates the need to allocate space on demand. 

Hi @Chris Hollis and @Hemanth 

Thanks for explaining this to me, I appreciate that 😉

I thought that since the size of the VMDK file was exactly the size provisioned, CV didn’t care about what was inside (nor about its structure) and just ‘copied' the entire (raw) file adding some compression or whatever.

@Hemanth - you’re absolutely right, however, there’s a fine document comparing both methods (thin vs thick); to make this long story short:

“The data we have collected reveals that VMware vStorage thin provisioning is at par in performance with the default method of provisioning in VMware (the usage of zeroes thick virtual disks).”

Also:

“ .. we determined that a workload run on a thin-provisoned disk performs very closely to that of a thick-provisioned disk, in both the zeroing and post-zeroing phases of disk growth.”

That is why I prefer thin provisioning over thick approach as it is much more flexible and almost as efficient.

If anyone would like to take a look at the document, I can share my copy as I don’t have the link to download it.

Regards,