Overview of Photon OS provides an introduction to Photon OS, its versions, and distinguishing features.
Product version: 4.0
This documentation applies to all 4.0.x releases.
This information is intended for Photon OS administrators who install and set up Photon OS.
1 - Introduction to Photon OS
Photon OS, is an open-source minimalist Linux operating system from VMware that is optimized for cloud computing platforms, VMware vSphere deployments, and applications native to the cloud.
Photon OS is a Linux container host optimized for vSphere and cloud-computing platforms such as Amazon Elastic Compute and Google Compute Engine. As a lightweight and extensible operating system, Photon OS works with the most common container formats, including Docker, Rocket, and Garden. Photon OS includes a yum-compatible, package-based lifecycle management system called tdnf.
When used with development tools and environments such as VMware Fusion, VMware Workstation, and production runtime environments (vSphere), Photon OS lets you seamlessly migrate container-based applications from development to production. With a small footprint and fast boot and run times, Photon OS is optimized for cloud computing and cloud applications.
2 - Flavours
Photon OS consists of a minimal version, a full version, RPM OSTree, and Photon Real-Time Operating System.
The minimal version of Photon OS is lightweight container host runtime environment that is suited to managing and hosting containers. The minimal version contains just enough packaging and functionality to manage and modify containers while remaining a fast runtime environment. The minimal version is ready to work with appliances.
The Developer version of Photon OS includes additional packages to help you customize the system and create containerized applications. For running containers, the developer version is excessive. The developer version helps you create, develop, test, and package an application that runs a container.
OSTree is a tool to manage bootable, immutable, versioned filesystem trees. Unlike traditional package managers like rpm or dpkg that know how to install, uninstall, configure packages, OSTree has no knowledge of the relationship between files. But when you add rpm capabilities on top of OSTree, it becomes RPM-OSTree, meaning a filetree replication system that is also package-aware.
Photon OS features a kernel flavor called ’linux-rt’ to support low-latency real time applications. linux-rt is based on the Linux kernel PREEMPT_RT patchset that turns Linux into a hard real time operating system. In addition to the real time kernel itself, Photon OS 4.0 supports several userspace packages such as tuned, tuna, stalld etc., that are useful to configure the operating system for real time workloads. The linux-rt kernel and the associated userspace packages together are referred to as Photon Real Time (RT).