If you are looking for free VMware backup solution then have a look on this software i.e. Ahsay software. Ahsay™ VMware backup module is designed for using in conjunction with AhsayOBM for fast and secure backup of guest virtual machines in VMware vSphere (ESX / ESXi), Server, Workstation, Fusion, and Player. VMware vCenter is supported by the latest AhsayOBM. Therefore, backup can be done with or without vCenter, depending on your configuration. VMware vCenter supported. The ONLY solution that supports vSphere (ESXi) Free version. Online backup of guest virtual machines, without interfering operation. for more information visit this link http://www.ahsay.com/jsp/en/home/index.jsp?pageContentKey=ahsay_products_overview

If you are looking for both ESXi free support (6.0 even) take a look at VSquare. http://www.vsquarebackup.com/

The free edition is limited but for a small reality I believe it may be more than enough.