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Backup sizes using VMware agent

Level 3

Hi guys,

I am in the process of trialling Backup Exec in conjunction with the VMware agent. I have a quick question. As a test I dumped 4 VMs using VMware VCB. The VMDKs are very large but are obviously not at full capacity. As a result the size of the files dumped totalled 70GB.

I have configured Backup Exec to backup the same 4 VMs. I have chosen not to use GRT and to my surprise the total amount of data dumped for the same 4 VMs is 160GB!

Obviously both VCB and Backup Exec remove whitespace otherwise the backups would have been much larger than that anyway. But I cannot account for the discrepency in the size difference between the two types of backup. Ultimately this will be coming accross a WAN link so obviously the smaller the backup size the better.

I am using vSphere4 U1 with the latest version of vCenter. I have just downloaded the latest version of Backup Exec 2010.

Anyone have any ideas on why this might be?

Employee Accredited Certified

Off hand I don't know the figures but I think Backup Exec needs a certain number of empty blocks in a row to decide that it is white space in the VMDK - might be that the VCB uses a different / smaller figure

Level 6
Partner    VIP    Accredited Certified
can you please check the used space on all the 4 vms. Example:

on one VM check the my computer and calculate  the total size used, the backup exec might take 5 gb more then what you see there.

Not applicable
I did an install for one of my clients and had the same issue.  Backup of a VMDK file backups the full disk size even though the disk is setup as with thin provisioning and there is only about 5 GB.

When we run a backup of the system as if it is real then the backup runs as expected.  Also in this environment there was one server that was created in ESXi and copied over and it runs as expected, but the others that were created in ESX from a template all backup as if they have full disks and there is only about 2 to 5 % full.

Any idea why and have you seen this in your environment?

Thank you in advance for your help.

Level 3

I'm experiencing the exact problem, a 50GB VMDK file that has been thin provisioned to 12GB is being backed up as 50GB.


Anyone know the answer?

Level 3

This is no longer an issue, although it appears to be backing up the data nothing is actually being allocated. Space is "reserved" but released when other backups require it.

Level 6
Partner Accredited

Have you done a "shrink disk" with the vmware tools on the virtual disk you are trying to backup ?

Level 3

I looked at that but is not the best solution, I'd rather find the solution through Symantec. I don't believe in 3rd party patch fixes.

Thanks anyway!

Level 4

I don't clear you question. but I think VCB should backup Image Vmware and Backup exec should backup only data, SQL file.


Example you should backup Image by VCB full once a week

and Backup exec backup data everyday.


Can you do with this solution?

Level 2


Same problem for me but i use FC between ESX and SAN (and ethernet between esx and backup exec).

ESXi 4.1Backup Exec  2010