Agent based backup is one of the oldest methods of managing and protecting computers connecting to a network. It is often referred to as guest based backup.

Features of an agent based backup:

  1. An agent is installed on every machine that connects to the network
  2. Every machine functions as if it were a physical server on the network
  3. The agent facilitates the streaming of data to the backup server in the Cloud
  4. Application administrators and computer administrators of the machine interact with the agent interface for all backup, recovery or reporting needs of data stored remotely in the backup server.

Cloud service providers, who entered the market in the infancy of the Cloud, adopted agent-based backup as a tested and proven method of protecting and managing individual computers on the network.  Statistics show that agent based management was adopted by about 46% of the people who created networks. Virtualization made no difference to the statistics, as users preferred to install an agent within the virtual machine and used the guest based backup systems to protect the information contained therein.

Why do users stick to agent based backup?  The reasons are many.  The learning curve is short as both physical and virtual machine agent based backup systems function in identical ways. Application managers are comfortable using this system as the agent runs on their machine. They can manage the remotely stored data or orchestrate a backup or recovery from their own desktops. Certain agents even display the remote drive as a local drive on the system. If virtual machines are in use—such as VMware Fault Tolerant virtual machines or Physical raw disk virtual machines—these machines can only be protected using agent based backup systems.

However, critics of the system have many faults to find with the efficiency of the agent-based backup.  They argue that agent based systems consume a significantly higher amount of CPU, memory, IO and network resources.  These agents have to be installed on every physical computer and virtual machine. Update of the agent is time consuming. The cost per license is high as opposed to other types of systems.  It does not accommodate the needs of virtualization efficiently. The system may breakdown if there is virtual machine sprawl. There is a lack of visibility when changing virtual infrastructure or VMware vSphere is used at client level.  There is no protection for virtual machines that are offline. Finally, the backup and recovery itself may be slow.