The service can scale linearly, so two boxes are twice as fast.
Immunity Inc. has released a security tool that can scan an astounding 1 million IP addresses per hour, discovering if they're susceptible to hacks that allow attackers to hijack servers or retrieve sensitive data.
The entry-level package of Swarm, as the service is called, is a 4U server that includes 10 virtual machines. This gives it the ability to test a huge number of IP addresses against a battery of sophisticated exploits. The software inside scales linearly, meaning two of the boxes can scan roughly twice as fast, and so on, said Dave Aitel, head of Miami-based Immunity. Prices begin in the "low six figures."
Read more:
http://arstechnica.com/security/2012/07/security-scanner-probes-1-million-ips-per-hour/