The linux virtual server

Introduction

The Linux Virtual Server ( LVS ) allows load reconciliation of networked services such as web and mail waiters utilizing Layer 4 Switching. It is highly fast and allows such services to be scaled to serve 10s or 100s of 1000s of coincident connexions

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The LinuxVirtualServerProject ( LVS ) implements layer4switching in the LinuxKernel. This allows TCP and UDP Sessionss to be load balanced between multiple realservers. Thus it provides a manner to scale Internet services beyond a individual host. HTTP and HTTPS traffic for the WorldWideWeb is likely the most common usage.

LVS itself runs on Linux, nevertheless it is able to lade balance connexions from endusers running any operating system to realservers running any operating system. Equally long as the connexions use TCP or UDP, LVS can be used.

LVS is really high public presentation. It is able to manage upwards of 100,000 coincident connexions. It is easy able to lade balance a concentrated 100Mbit ethernet nexus utilizing cheap trade good hardware. It is besides able to lade balance saturated 1Gbit nexus and beyond utilizing higher-end trade good hardware.

Virtual waiter is a extremely scalable and extremely available waiter built on a bunch of existent waiters. The users interact with the bunch system as if it were merely a individual high-performance practical waiter. See the undermentioned figure.

The existent waiters and the burden balancers may be interconnected by either high-velocity LAN or by geographically dispersed WAN. The burden balancers can despatch petitions to the different waiters and do parallel services of the bunch to look as a practical service on a individual IP reference, . Scalability of the system is achieved by transparently adding or taking nodes in the bunch. High handiness is provided by observing node failures and reconfiguring the system suitably.

1.1 Why practical waiter?

With the explosive growing of the Internet and its progressively of import function in our lives, the traffic on the Internet is increasing dramatically, which has been turning at over 100 % one-year rate. The work load on the waiters is increasing quickly so that waiters will be easy overloaded for a short clip, particularly for a popular web site. To get the better of the overloading job of the waiters, there are two solutions. One is the individual waiter solution, i.e. to upgrade the waiter to a higher public presentation waiter, but it will shortly be overloaded when petitions increases so that we have to upgrade it once more, the upgrading procedure is complex and the cost is high. The other is the multiple waiter solution, i.e. to construct a scalable web service system on a bunch of waiters. When burden additions, we can merely add a new waiter or more into bunch to run into the increasing petitions, and trade good waiter is of highest performance/cost ratio. Therefore, it is more scalable and more cost-efficient to construct server bunch system for web services.

1.2 Where do we utilize LVS?

  • For higher throughput. The cost of increasing throughput by adding existent waiters in an LVS additions linearly, whereas the cost of increased throughput by purchasing a larger individual machine additions faster than linearly
  • For redundancy. Individual machines can be switched out of the LVS, upgraded and brought back on line without break of service to the clients. Machines can travel to a new site and brought on line one at a clip while machines are removed from the old site, without break of service to the clients.
  • For adaptability. If the throughput is expected to alter bit by bit ( as a concern builds up ) , or rapidly ( for an event ) , the figure of waiters can be increased ( and so decreased ) transparently to the clients.

1.3 Goals

The basic end of the Linux Virtual Server Project is to:

Construct a high-performance and extremely available waiter for Linux utilizing constellating engineering, which provides good scalability, dependability and serviceableness.