VPS Hosting Stuff

Nice discussion going on slashdot.org about performance differences of xen and openVZ.

An anonymous reader writes Compared to an operating-system-level virtualization technology like OpenVZ, Xen — a hypervisor-level virtualization technology that allows multiple operating systems to be run with and without para-virtualization — trades off performance for much better isolation and security. OpenVZ’s performance advantage due to running virtual containers in a single operating system kernel can be significant. A performance evaluation study (PDF) done by researchers at the University of Michigan and HP labs provides insight into how big a performance penalty Zen pays and what causes the overheads (primarily L2 cache misses).

From the report: “We compare both technologies with a base system in terms of application performance, resource consumption, scalability, low-level system metrics like cache misses and virtualization-specific metrics like Domain-0 consumption in Xen. Our experiments indicate that the average response time can increase by over 400% in Xen and only a modest 100% in OpenVZ as the number of application instances grows from one to four… A similar trend is observed in CPU consumptions of virtual containers.”

Read more from : http://slashdot.org/article.pl?sid=07/05/15/019251

OpenVZ (the basis for the commercial Linux platform Virtuozzo) and Xen could be viewed as competing VPS platforms, however, the truth of the matter is that they are very different - read on to find out how the OpenVZ and Xen VPS platforms work, how they differ, and why the choice of OpenVZ or Xen is an easy one to make.

OpenVZ Virtualization

openvz vps hosting

OpenVZ is an operating system-level virtualization platform based on a single Linux kernel which has been modified to support multiple Linux virtual environments (more commonly referred to as virtual private servers).

The modified OpenVZ kernel isolates the file system, memory, and processes for each virtual environment, providing OpenVZ VPS administrators with full root access and all of the commands normally associated with a dedicated server.

Xen Paravirtualization

xen vps hosting

Xen is a paravirtualization platform which is very similar to hardware emulation. Paravirtualization works by creating an interface between the virtual environment’s operating system and the hardware which queues and responds to operating system requests from operating systems modified to interact with the paravirtualization interface.

This key difference from operating system-level virtualization allows Xen VPS administrators to modify their kernel modules, utilize swap space to meet memory allocation demands, and watch their Xen virtual private server’s boot process as Linux mounts virtualized devices.

Key Differences:

Below is a quick run down of various types of VPS control panels that are available:

• Virtuozzo - One of the leading VPS control panels. Swsoft, the developer of Virtuozzo are allowing people to handle their VPS�s exactly like dedicated servers. With many options supported by the product you could do just about anything. Swsoft uses a technology different then others.

  Virtuozzo allows users to use “Burstable RAM”. “Burstable RAM” is a technology supported by swsoft. Whenever a user needs more RAM than usual and there is a surplus of RAM used by other users on the server, “Burstable RAM” will allow that user to use more RAM for a limited time. This ability makes Virtuozzo very flexible. http://www.swsoft.com

• Vmware - Another leading VPS control panel in the web sector. Vmware allows users exactly the same opportunities given by Virtuozzo, although it doesn�t support the “Burstable RAM” technology. However it supports a different technology called “Multi-OS”. “Multi-OS” in other terms means, “Multi-Based Operating System”. With Vmware you can easily provide more then one operating system working on the same server. This allows companies to reduce costs by not having to purchase different server for different operating systems. http://www.vmware.com
• Xen - A newborn product still underdevelopment. However it is very popular and many companies have already adopted this VPS control panel because of it’s efficiency in limiting the amount of system resources used.

  Normally a VPS control panels use high resources when running on a server. But as Xen uses different technique of resource management it has the same features provided by Virtuozzo (except that it doesn�t support “Burstable RAM” technology) and yet does not consume as much resources.

  However please remember that Xen is still under development so there are a few bugs that need to be addressed and improvements that need to be made. http://www.cl.cam.ac.uk/Research/SRG/netos/xen/