Sun Microsystems 10 manual Solaris Containers and Solaris Zones, Overview

Version 3.1-enSolaris 10 Container Guide - 3.1 2. Functionality Effective: 30/11/2009

2. Functionality

2.1. Solaris Containers and Solaris Zones

2.1.1. Overview

[ug] Solaris Zones is the term for a virtualized execution environment – a virtualization at the operating system level (in contrast to HW virtualization).

Solaris Containers are Solaris Zones with Resource Management. The term is frequently used (in this document as well) as a synonym for Solaris Zones.

Resource Management has already been introduced with Solaris 9 and allows the definition of CPU, main memory and network resources.

Solaris Zones represent a virtualization at the interface between the operating system and the application.

∙There is a global zone which is essentially the same as a Solaris operating system was in earlier versions

∙In addition, local zones, also called nonglobal zones, can be defined as virtual execution environments.

∙All local zones use the kernel of the global zone and are thus part of a single physical operating system installation – unlike HW virtualization, where several operating systems are started on virtualized hardware instances.

∙All shared objects (programs, libraries, the kernel) are loaded only once; therefore, unlike for HW virtualization, additional consumption of main memory is very low.

∙The file system of a local zone is separated from the global zone. It uses a subdirectory of the global zone's filesystem for a root directory (as in chroot environments).

∙A zone can have one or several network addresses and network interfaces of its own.

∙Physical devices are not visible in local zones (standard) but can optionally be configured.

∙Local zones have their own OS settings, e.g. for name service.

∙Local zones are separated from each other and from the global zone with respect to processes, that is, a local zone cannot see the processes of a different zone.

∙The separation extends also to the shared memory segments and logical or physical network interfaces.

∙Access to another local zone on the same computer is therefore possible through the network only.

∙The global zone, however, can see all processes in the local zones for the purpose of control and monitoring (accounting).

App

Local	Local	Local
zone	zone	zone
Global zone

OS

Server

Figure 1: [dd] Schematic representation of zones

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