Building clusterized proxy farms using LVS

Introduction

Sometimes, you just need to build a proxy farm with the following needs:

• you need high-availability, because of your SLA.
• you need load balancing, because you're serving numerous Kusers.
• you need caching with Squid.
• you need extra-services over Squid (URL filtering with DansGuardian/SquidGuard, Antivirus softwares, ...)
• you need scalability because you want to be able to grow.

In these cas, you've got plenty of answers to proceed. LVS is one of them (probably the best suited anyway).

But as you're doing extra-services over Squid, the base LVS ldirectord tests won't be sufficient.

This page explains how to make some more advanced tests to be sure some extra-services will be checked too, and the corresponding realserver service will be dropped down if one of the extra service (or Squid itself) is not available.

It present a proposed patch to ldirectord to do so.

Architecture

The system architecture of web cache cluster using LVS is illustrated in the following figure.

FIXME

• it use LVS with Ultramonkey 3 settings for a Streamline High Availability and Load Balancing setting.
• it is base on the usage for Squid + DansGuardian (but could feet for any Squid + *).