Features of Virtuozzo

[eUKShane]

The concept of Virtuozzo Virtual Private Servers is distinct from the concept of traditional virtual machines in the respect that Virtual Private Servers (VPS Hostings) always run the same OS kernel as the host system (Linux on Linux, Windows on Windows, etc.). This single-kernel implementation technology allows to run Virtual Private Servers with a near-zero overhead.

Thus, Virtuozzo VPS Hostings offer an order of magnitude higher efficiency and manageability than traditional virtualization technologies.

OS Virtualization :

From the point of view of applications and Virtual Private Server users, each VPS Hosting is an independent system. This independency is provided by a virtualization layer in the kernel of the host OS. Note that only an negligible part of the CPU resources is spent on virtualization (around 1-2%). The main features of the virtualization layer implemented in Virtuozzo are the following:

- VPS Hosting looks like a normal Linux system. It has standard startup scripts, software from vendors can run inside VPS Hosting without Virtuozzo-specific modifications or adjustment;

- A user can change any configuration file and install additional software;

- Virtual Private Servers are fully isolated from each other (file system, processes, Inter Process Communication (IPC), sysctl variables);

- Virtual Private Servers share dynamic libraries, which greatly saves memory;

- Processes belonging to a VPS Hosting are scheduled for execution on all available CPUs. Consequently, VPS Hostings are not bound to only one CPU and can use all available CPU power.

Network Virtualization :

The Virtuozzo network virtualization layer is designed to isolate VPS Hostings from each other and from the physical network:

- Each VPS Hosting has its own IP address; multiple IP addresses per VPS Hosting are allowed;

- Network traffic of a VPS Hosting is isolated from the other VPS Hostings. In other words, Virtual Private Servers are protected from each other in the way that makes traffic snooping impossible;

- Firewalling may be used inside a VPS Hosting (the user can create rules limiting access to some services using the canonical iptables tool inside the VPS Hosting). In other words, it is possible to set up firewall rules from inside a VPS Hosting;

- Routing table manipulations are allowed to benefit from advanced routing features. For example, setting different maximum transmission units (MTUs) for different destinations,specifying different source addresses for different destinations, and so on.

Virtuozzo File System (VZFS) :

VZFS is a file system that allows to share common files among multiple VPS Hostings without sacrificing flexibility. It is possible for VPS Hosting users to modify, update, replace, and delete shared files. When a user modifies a shared file, VZFS creates a private copy of the file transparently for the user. Thus, the modifications do not affect the other users of the file. Main benefits of VZFS are the following:

- It saves memory required for executables and libraries. A typical VPS Hosting running a simple web website hosting might consume around 20–30 MBytes of RAM just for executable images. Sharing this memory improves scalability and total system performance;

- It saves disk space. A typical Linux server installation occupies several hundred MBytes of disk space. Sharing the files allows you to save up to 90% of disk space;

- VZFS does not require having different physical partitions for different VPS Hostings or creating a special “file system in a file� setup for a VPS Hosting. This significantly simplifies disk administration;

- Disk quota enables the administrator to limit disk resources available to a VPS Hosting on-the-fly, in the same manner as the standard disk quota system works on a per-user basis. Disk quota for users and groups inside VPS Hostings is also supported.

Templates :

A template (or a package set) in Virtuozzo is a set of original application files repackaged for mounting over Virtuozzo File System. Usually it is just a set of RPM packages for Red Hat like systems. Virtuozzo provides tools for creating templates, installing, upgrading, adding them to and removing them from a VPS Hosting. Using templates lets you:

- Share the RAM among similar applications running in different VPS Hostings to save hundreds of megabytes of memory;

- Share the files comprising a template among different VPS Hostings to save gigabytes of disk space;

- Deploy applications simultaneously in many VPS Hostings;

- Use different versions of an application on different VPS Hostings (for example, perform an upgrade only in some VPS Hostings).

There are two types of templates in Virtuozzo. These are OS templates and application templates. An OS template is an operating system and the standard set of applications to be found right after the installation. Virtuozzo uses OS templates to create new Virtual Private Servers with a preinstalled operating system. An application template is a set of repackaged RPMs optionally accompanied with configuration scripts. Virtuozzo uses application templates to add extra software to the existing Virtual Private Servers. For example, you can create a Virtual Private Server on the basis of the redhat9 OS template and add the MySQL application to it with the help of the MySQL Server template.

Resource Management :

Virtuozzo Resource Management controls the amount of resources available to Virtual Private Servers. The controlled resources include such parameters as CPU power, disk space, a set of memory-related parameters. Resource management allows Virtuozzo to:

- Effectively share available Hardware Node resources among VPS Hostings;

- Guarantee Quality-of-Service (QoS) in accordance with a service level agreement (SLA);

- Provide performance and resource isolation and protect from denial-of-service attacks;

- Simultaneously assign and control resources for a number of Virtual Private Servers;

- Manage a multitude of Hardware Nodes in a unified way by means of Virtuozzo Management Console (VZMC);

- Collect usage information for system health monitoring, etc.

Resource Management is much more important for Virtuozzo than for a standalone computer since computer resource utilization in a Virtuozzo-based system is considerably higher than that in a typical system.

That's it :eek:
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Best Regards,
UKShane
http://www.eukhost.com