CoreOS and Joyent's SmartOS/Triton have worked to redefine, in radically different ways, what an OS needs to be to run applications at scale in the cloud.
Now another candidate is set to join the ranks of maverick cloud OSes: OSv, open source, hypervisor-optimized, and "designed to run an application stack without getting in the way."
OSv runs existing Linux applications, but is not itself Linux; it's entirely new and written from the ground up in C/C++. It can run on a slew of hypervisors and virtual machine systems, or in cloud environments like Amazon EC2 or Google Compute Engine. The company claims significant performance gains for apps running on OSv, saying the boost comes from design choices that rely on the hypervisor, rather than separate user and kernel address spaces, for keeping elements isolated.
Instead of using Docker containers, OSv uses its own application-image system called Capstan. Apps packaged with Capstan are said to be "only 12-20MB larger than [the] application itself" and are complete virtual images that can run on any hypervisor that supports OSv.
The people heading up Cloudius, the company sponsoring the project, have been heavily involved in the business of virtualization for some time now. Cloudius CTO Avi Kivity and CEO Dor Laor both helped create the original incarnation of the KVM hypervisor at Qumranet, and later helped maintain that project for Red Hat after the latter company acquired it.
The company has already packaged several applications as virtual appliances for OSv: Memcached (and a flash-storage optimized variant called Flashcache), Redis, and Cassandra. The company claims Java and its frameworks, along with Hadoop and NoSQL, are "being optimized and integrated to run on top of OSv."
OSv is meant to be a boon to management as well. It exposes its most crucial management interfaces as REST API endpoints and provides a mechanism for passing configuration data to an instance when it's spun up. Support for monitoring OSv instances through New Relic is also included, along with Jolokia for directly managing Java apps by way of JSON and REST.
Some of these early-stage decisions are savvy -- such as, providing close integration for enterprise Java applications. But entirely eschewing existing container technologies might come off as foolhardy, even for early adopters who haven't yet committed to containers themselves. One factor that might aid OSv in the short run is a converter that repackages Docker containers to work with OSv for the sake of convenience, in much the same way images for one variety of VM can be converted to run on another.
Users can download and run instances of OSv on their own hardware or on a cloud server, and the source is available under the BSD license. The company's also trying to get early adopters to sign up for a private beta program, where more bleeding-edge versions of the code will be provided.
[Edited to add details about Cloudius's personnel.]