…And in many ways, workload management – allocating CPU, memory, and I/O resources to applications as they are running to avoid resource-hogging – is a better approach to more fully utilizing a system than virtualizing a machine.
…The secret sauce in Load Manager that allows it to throttle Windows and Linux workloads is a software shim that sits between a hypervisor or an operating system and its applications as they run. This shim has its origins in a checkpoint/restart program used in HPC clusters, which kept track of the state of all the nodes in a cluster.
It has been modified to intercept all library calls to allocate memory and I/O from applications as they are running. The applications do not have to be modified for this shim to work and neither do the operating systems or hypervisors. In fact, none of the software is aware that there is a traffic cop on the system actually controlling what resources different bits of software get.
Workload management has traditionally been a much less developed discipline on x64 Windows and Linux while virtualization has taken off. They two approaches are complementary (and both are needed), but Librato exposes some performance knobs that some users will need, especially in applications where heavy I/O loads make virtualization a bad idea.
Pricing starts at $200 per socket per year, lower in volume.