Agentless antivirus is considered in the context of securing virtualized computers. Traditional agent-based security is a poor choice for virtual environments because of the dynamic nature of virtual machines. With agentless antivirus you can protect all the virtual machines on the host without having to deploy an agent to each virtual machine. Instead you offload your antivirus scans to a virtual host.
When antivirus is run with agents, there is a high demand on computing resources because the antivirus software simultaneously scans all the virtual machines on a physical host. This can cause what is called an AV storm a bombardment of the underlying pool of memory, storage, and CPU resources, resulting in slower service.
The benefits of going agentless include:
Trend Micro™ Deep Security™ provides agentless security for virtualized data centers, virtual desktops, and cloud environments. Deep Security’s agentless protection offers significantly higher virtual machine densities over leading traditional agent-based security solutions. It enables agentless security through the offloading of security processing to dedicated, security-hardened virtual machines. Tightly integrated modules easily expand the platform to ensure server, application, and data security across physical, virtual and cloud servers, as well as virtual desktops.