[Icecast] Max Icecast Listeners

Michael Smith msmith at xiph.org
Tue Jul 26 18:11:09 UTC 2011

On Tue, Jul 26, 2011 at 10:52 AM, Raymond Lutz <raylutz at cognisys.com> wrote:
> I am curious if anyone has had enough experience to know --> how many
> simultaneous listeners can be supported by typical server boxes,
> assuming unlimited bandwidth is available?

Icecast scales pretty well, to the point that assuming unlimited
bandwidth is not an appropriate assumption.

> My specific case:
> My server (http://www.AirProgressive.org) is on a Linux VPS server
> located in a datacenter and on a optical backbone so that bandwidth is
> not the problem. Each connection I am running is at 32kbps and 22050 Hz
> sampling rate (mono) since the program is "talk radio". The bandwidth
> available per month is 6000 GB and at an average of 4.5 hours per week
> of listening, which is what similar stations had in this area of the
> same genre, I can service about 21,000 listeners per month.  The peak
> would be at least 562 listeners at any one time, which is the average.
> Let's just assume the peak is 10,000 listeners at a time. How many
> servers do I need to support that? (and more importantly, how do I
> figure it out?)

At 32 kbps? About one. Note that this is well over 300 Mb/s; you
should ensure that your network connection is actually able to sustain

See the load tests on the icecast website that were done quite a few years ago.

> Q2: does icecast provide any warnings when it finds it is unable to keep
> up with the workload? What sort of failure mode will occur? Gaps in the
> transmission, dropped listeners, ?

The log files will show dropped listeners, but there's no good
high-level interface to show you that cpu load is a problem.


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