ZONE's in Solaris

Zone: A zone is an OS level virtualization introduced from Solaris 10 to give isolation & security to the applications on server. Main advantage is data center consolidation. We can combine multiple physical servers into one physical server and provide same environment for all the applications. From2008 release a new concept called "BRAND ZONE" has been introduced. This enables us to run Solaris 8/9/10 on Sparc servers and any Linux flavors on X86 servers. A maximum of8192 zones can be created inside one physical server independent of Hardware configuration.

PURPOSE: OS level virtualization.

TYPES: Global zone and Non global zone.

NON-Global zone: Sparc root, whole root and brand zone

FILES: /etc/vfstab , /etc/zones

PACKAGES: SUNWzoner

DAEMONS: zoneadm & zxched

COMMANDS: #zonecfg, #zoneadm & #zlogin

STATES: configured, installed, incomplete, ready, running & shutdown/halt

There are two types of zones - "global zones" and "non global zone"

Global zone: Login as first instance
Non Global zone: It is an virtualized OS in a server.

Features of Global zone: It is a default zone used for system wide configuration and control.
Zone id = 0. It provides a single bootable instance of Solaris environment.
Contains info of all the devices and full installation packages of Solaris 10 OS. Contains its own configuration :- hostname, IP address, User info.....etc
It is the only zone which is aware of Non Global Zone. It is the only zone from which all the Non Global Zone can be managed.

Features of Non Global Zone: It is created by global zone and is also managed by it. A non global zone is assigned a zone id by the system when it is booted. Whenever a Non global zone is rebooted the zone ID changes. Non global zone shares the kernell from Global zone.
A non global zone is not aware of the other non global zones and it cannot administer itself. It contains additional software which is used at installation time It contains a sub set of packages from Global zone which are required to boot and run the OS.

Zone root path:
1. Sparc root zone: In this instance only root "/" is copied and other files and shared. Minimum space required is 100mb.
2. Whole root zone: In this instance everything is copied. Minimum space required is 4Gb.

Sparce Root Zone: Sharing is optimized by implementing read only loop back filesystem from Global zone and only installs a subset of system root packages locally. Majority of Filesystem is share from Global zone. Minimum space requirement is 100 mb.

Whole Root Zone :  All required packages are copied to zone's private Filesystem and minimum size required is 4 gb.

Daemons in Zones : Two major daemons run - zoneadm & zsched


Zoneadm : This daemon starts when a zone needs to be managed. An instance of zoneadm daemon will be started for each zone. Hence it is not uncommon to have multiple instance running a single server.
This daemon is responsible for the following tasks.
- Allocates the zone id and starts Zsced process.
- Sets system wide resource controls.
- Plumbs the virtual network interface.
- Mounts the loopback Filesystem and shares the resources from Global Zone.

Zsced : Zone scheduler daemon is started by zoneadm and exists for each active zone. A zone is said to be active when it is in "ready", "running" or "shutdown" states. The job of this daemon is to keeptrack of kernell threats running within the zone.

Zone States: 


Configured: A zone in this state has completed configuration, confirmed storage and additional configuration must be done after initial reboot.

Incomplete: This state is shown during installation or un-installation process. After this task is completed the state changes to installed / uninstalled state.

Installed: Confirmed configuration state. #zoneadm command is used to verify that the zone is going to run in the specified environment. The base binaries required to run and boot the zone are copied from Global Zone to Non Global Zone. Virtual environment is not set at this stage.
Ready: Kernell creates Zsced process and virtual environment is set. Network interfaces are plumbed and Filesystem's are mount and Zone ID is assigned by the system.

Running: A zone enters this state when the first user process is created. This is a normal state of operational zone.

Shutdown: This is a transitional state, only visible when a process is being halted or cannot shutdown for any reason.