Avamar 5.0 VMware Image Backup Error

March 4, 2010

**As of June 2010, this issue has been resolved with VMware release vCenter 4.0 Update 2.0**

I recently had an issue trying to backup a virtual machine with EMC Avamar version5’s VMware Image Proxy. When kicking off the VM backup, we would see the following errors in in the Avamar backup job log:

“avvcbimage Error : vmx file is suspiciously small (under 30 bytes), please examine the log on the Avamar Administrator for root cause analysis”

The following screenshot are the tasks that are being performed in vCenter, as you can see we get an error accessing the vmx and nvram files inside the datastore:

The problem is a Vmware bug in virtual center where vCenter passes

Avamar an empty vmx file. The problem is caused by special characters in the datastore name or VM display name or vmx file name.


1) Move datacenters located in folders/sub-folders to the root level.


2) Specify –x22=8192 flag in the dataset dialog (for VM’s only, will not work for templates).
This allows the backup to succeed even if the vmx file (that contains the VM configuration) is not backed up. The restore for this backup will work for restore to original and restore to existing, but not for restore to new. To do restore to new, you need to manually create a VM with the same configuration as the original VM, and do restore to existing to the newly created VM.

1. Launch the Avamar Administrator

2. Select “Back and Restore”

3. Find a virtual machine you would like to backup and highlight it

4. Make sure the “Windows VMware Image” plug-in is selected on the right

5. Select the “Actions” pull down menu and select “backup now”

6. The “On Demand Backup Options” windows should open

7. Adjust the “Retention Period” to 3 days

8. Click the “more options” button

9. Click the more button

10. In the “enter Attribute” box type –x22 and in the “enter attribute value” box type 8192

11. Then click the plus sign button and click ok

12. The backup should start now and you can view it from the activity window



  1. I had the same problem. Your solution worked perfectly! Thanks for the help πŸ™‚

    However, I had to use x22=8192 instead of -x22=8192

    I have no idea what this switch is or what it means, but it worked perfectly. Thanks again.

  2. Hi, thanks for this , you saved me a ton of trouble and time. I just wanted to note that this bug is now re-occurring in ESX 4.1 and the latest Avamar – the workaround/fix is to ensure the VCBUSER backup account has ADMINISTRATOR privs in vcenter role – turns out we were using the “out-of-the-box” vcbuser role, which apparently has not enough rights to backup the .vmx file, which makes recovery a challenge to say the least.. thanks again, cheers – jamie

    • Hey Jamie
      If you have a EMC PowerLink Account, download the latest VMware Guide for Avamar 5.0. There is a whole section in there now that walks you through adding the correct security privledges to the AD account you use to authenticate with the vCenter client. I had the same issue as you several months ago trying to use the old VCBUser.

  3. Thanks Hugh, funny (Sad) part is this – the avamar grid was installed and configured by EMC just last week. it is indeed the latest version (Or so i have been assured?!).. I read the admin guide they sent me from top to bottom – nothing about that part on the backup user, just the installation user for putting vcenter into avamar!!?? … (I’ll go back and look (unless you have a link? I do have powerlink acct?), but… i’ll be darned – the EMC installer engineer opened an SR as Sev 1 and the Avamar remote engineer webexed in and fixed it right away .. It’s funny – I love emc hardware, but wow the software i’ve come to consider as “puzzle-ware” – i am coming from EMC Networker, so I am loving avamar so far. vtls and vtapes and pools begone!! :)) .. So.. thanks again for your blog, it’s helped us out a lot actually – hopefully we can help contribute in the future if you keep it going – there is a major lack of avamar (meaning NON-emc) resources out there, (well the list-serv at temple.edu is probably ok, but it’s very low-volume so far.. :\ cheers, and happy holidays! Jamie

    • Sorry, I told you wrong, the information is actually in the Avamar version 5 latest release notes as an appendix to the VMware Guide

      See: Avamar for VMware Guide The following information should be added as a new appendix to the Avamar for VMware Guide: Minimum Required vCenter User Account Permissions In high-security environments, you can restrict the vCenter user account permissions required to configure and administer the Avamar VMware image backup and restore feature (page 22) to all of the following: Datastore > € Allocate Space € Browse datastore € Low level file operations € Move datastore € Remove datastore repluser 9RttoTriz Account for internal use by Avamar Administrator server for replication. root avam@r Default root account on an Avamar VMware image backup proxy 34 AVAMAR 5.0 RELEASE NOTES VMWARE IMAGE AVAMAR BACKUP PROXY ADMINISTRATORDocumentation Errata € Remove file € Rename datastore Folder > € Create Folder Global > € Cancel task € Log event € Settings Network > € Assign network € Configure Resource > € Assign virtual machine to resource pool Sessions > € Validate session Tasks > € Create task € Update task Virtual machine > Configuration > € Add existing disk € Add new disk € Add or Remove device € Advanced € Change CPU count € Change Resource € Disk change Tracking € Disk Lease € Host USB device € Memory € Modify device setting € Raw device € Reload from path € Remove disk € Rename € Reset guest information € Settings € Swapfile placement € Upgrade virtual hardware € Extend Virtual disk 35 AVAMAR 5.0 RELEASE NOTES Documentation Errata Virtual machine > Interaction > € Power Off € Power On € Reset Virtual machine > Inventory > € Create new € Register € Remove € Unregister Virtual machine > Provisioning > € Allow read-only disk access € Allow virtual machine download € Mark as Template Virtual machine > State € Create snapshot € Remove Snapshot € Revert to snapshot

  4. […] I was planning to write the exact steps I followed but while searching the internet I noticed one of the Varrow bloggers Hugh Griffin had beaten me to it and posted about the error and the same steps I followed(the second workaround).So due to my hating people who repeat my solutions to problems on their blogs with minimal credit I felt it was only fair to give him the credit so here is his blog posting of the solution β€œAvamar 5.0 VMware Image Backup Error” […]

  5. Guys,
    I am getting the same error using vSphere 5.0 with Avamar 6.1. Is this situation still around with these versions?

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