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What does "VMDK Type" Option Exactly mean ?

Level 6

As per Doc:


The virtual disk (vmdk) files are optimized so that only the necessary blocks are transferred. If a virtual machine has a 200-GB disk but only 10 GB are used, the vmdk file that is sent to the proxy is 10 GB plus the grain tables that describe the optimized vmdk files. 0-optimized is the default. If the policy storage unit is not PureDisk, accept the default.

When i initiate Backup for VM's with 20 GB each; VCB is copying Full 20 GB VMDK to Mount Point even though the 20 GB VM have only 10 GB used space.

What is making wrong here !

Level 6
I am backing up only Windows VM's 

Level 6

- update -

This option requiresVCB1.1 and ESX server 3.5 or later.

Level 6
NO Mine is Having Suited Software Availability

VM Consolidated Backup Framework -
ESX Version : 4.0

Level 6
try to backup your machine using vcbmounter (command line) and check for vmdk size.


Not applicable
You could have 10GB of deleted data in the VM and this is seen as block data to send.

when VMware Consolidated Backup dumps image level backups VCB only dumps used diskspace. Unfortunately for us VCB does this by checking at block level if it contains only zero’s or not. If it contains only zero’s the block is considered empty, but an Operating System doesn’t zero out the disk space that contained the files when a file is deleted. An Operating System only clears the pointers to these files. This is why you could have a disk with only 4GB of used space and a 6GB VCB dump.

For more details on this,

Level 6
I think Script should help me something in this case, but i I have a VM with 100 GB and used space of Only 40GB. i have checked with server owner, found that they didnt ever used more than that space.

I have logged symantec case for this, but case got closed saying" veritas is calling vcbmounter to do optimzed backup but VCB is not doing that job, so Vmware should help here.

I just checking with my VMware Experts.. Will post the updates.

Tell me one thing, What other possibilites for VCB VMDK Optimize not work.