Deploy the VDP successfully does not mean that it will work and like you see on the Interoperability Matrix, VDP 6.1 does not support ESXi 4.x.
See what VMware says on Admin Guide found here: http://pubs.vmware.com/vsphere-60/topic/com.vmware.ICbase/PDF/vmware-data-protection-administration-...
Software Requirements VDP 6.1 requires the following software:
vCenter server 5.5 or later
VDP 6.1 supports the Linux-based vCenter server virtual appliance and the Windows-based vCenter server.
vSphere web client
The following link provides information about current vSphere web browser support:
https://pubs.vmware.com/vsphere-60/index.jsp?topic=%2Fcom.vmware.vsphere.install.doc%2FGUID-F 6D456D7-C559-439D-8F34-4FCF533B7B42.html&resultof=%22web%22%20%22client%22
Web browsers must be enabled with Adobe Flash Player 11.3 or later to access the vSphere web client and VDP functionality.
vSphere host 5.0 or later
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Richardson Porto
Senior Infrastructure Specialist
LinkedIn: http://linkedin.com/in/richardsonporto