The proxy servers are the real workhorse of the Veeam Backup & Replication, especially CPU resources. With the default compression options, use the following guidelines for building proxies:
• Virtual Proxies — 1 vCPU + 2GB of RAM per vCPU
•Physical Proxies — 1 CPU Core + 2GB of RAM per CPU core
For example, a physical server with two quad-core processors, should ideally be sized with at least 16GB of memory and would then be able to run 8 concurrent tasks using the default compression options (a task refers to a single virtual disk being processed; to read more about parallel processing and setting the number of concurrent tasks, refer to Parallel Processing section above).
To protect VMs running on ESXi 5.5, you must deploy backup proxies on machines running a 64-bit version of Microsoft Windows.