Archives for multi server

Vicidial Scaling and Fault Tolerance Notes

One of the most impressive features of Vicidial is its ability to scale, while at the same time enabling fault tolerance.  It has the ability to scale from a few users, to hundreds of users and thousands of simultaneous calls.  This is accomplished through the multi-server architecture ability of Vicidial and the ability to separate the various components of Vicidial onto separate servers and provide redundancy.

Single Server Setup

In the figure below you can see a basic Vicidial installation.  In the most basic configuration, you would typically have less than 50 agents which would only require one server.  Since the installation is so small (and most likely the call volume is low as well) you would most likely only have a single dial tone provider.  All of the services would run on the single server and all of the agents would connect to the same server.

Vicidial Single Server Installation

A Vicidial Single Server Installation

This configuration is the simplest, easiest to configure, and the cheapest, but subsequently the least fault tolerant.  The performance limits are determined by the hardware of the single server.  It has been our experience that while the recommended configuration is a maximum of 50 agents for this configuration, with a low volume call center, it is possible to increase that number to as much as 100 with some parameter tweaking.

Multi-Server Setup

As the call volume and number of call center agents increases, the number of servers required can be increased to handle the increased load.  We have built call centers with 300+ agents that do outbound dialing at a ration of 5:1 – meaning 1500 simultaneous calls.  And the Vicidial group has documented cases of even larger installations.


Vicidial Multi Server

A Vicidial Multi-Server Installation

The multi-server installation requires several components:

  • Primary Database Server – This server contains the master operational database and is the “key” server for the proper operation of the system.  It should be the fastest server with the most RAM in the entire group of servers
  • Secondary Database Server – This server serves as a backup for the primary database server and is used for redundancy, as well as to offload report generation from the Primary server to increase performance
  • Web Server – Because Vicidial is a web-based call center system, a high performance web server is key to proper operation.  In smaller setups, this can be handled by the same server as the database server, but as web traffic increases, it is best to offload the web traffic to a separate server.  The added benefit is that a separate web server is more secure if the Vicidial system has to be exposed to the Internet.
  • Network Attached Storage (NAS) Server – Vicidial has the ability to record EVERY call.  This will take up a very large amount of disk space.  A NAS device can provide a large amount of storage at a cheap price where you can store all your recordings in a central location and access them through the Vicidial interface.  Additionally, you can use the NAS device to store backups of each server’s configuration.  Finally, as an added benefit, many NAS device manufacturers have the ability to sync any storage in the device to cloud services (such as Amazon), thus making all the information available anywhere.
  • Telephony Servers – This is where the “heavy lifting” is done for Vicidial.  These servers are responsible for making and receiving the phone calls within Vicidial.  Some of these servers can also be dedicated to hosting specific agents to balance agent load across multiple servers.  Here’s where the magic truly happens.  Need more agents or more calls?  Simply add more telephony servers (assuming you have the database and web server infrastructure already in place).  The other great part is that these servers require the least amount of hardware and disk space since all they are doing is making phone calls, essentially.  Plus, if one of the telephony servers dies, the system as a whole is only mildly affected.  At the very most, a few agents will not be able to log in and dialing capacity will be reduced.  But the rest of the system will continue to operate

In order to get this level of performance and fault tolerance in a proprietary system, it would cost hundreds of thousands of dollars.  This type of setup can accomplish that in a fraction of the cost.


As you can see, Vicidial has the ability to scale from small call centers to very very large systems when designed properly.  Contact Verterion today at for more information about designing or expanding your Vicidial system.

WP2Social Auto Publish Powered By :