1 Mar 2018

[Blog] What hardware do I need to run MistServer?

Hey everyone! A very common question we get is about the hardware requirements for MistServer. Like any good piece of software there is no "real" hardware requirement in order to use MistServer, but there is definitely a hardware requirement for what you want to achieve media streaming wise. I’ll go over the main categories for hardware and leave you with a few simple calculators to decide on your hardware specs.

How do I decide on the hardware?

We tend to divide the hardware in 4 necessary categories: CPU, RAM, bandwidth and storage. Each category is important, but depending on your streaming media needs one might be more important than the other.

Processor (CPU)

The CPU is obviously important as it handles all the calculations/requests in your server. Luckily MistServer itself is not that demanding on your system. If you are running other applications aside from MistServer they will probably be more important for your processor choice than MistServer. As MistServer is heavily multi processed it does benefit from processors that can handle more threads or have more cores.

To give you something tangible: if you go to the cpubenchmark mega list every 3.4 points on CPU mark equals one viewer. For example the Intel Xeon E5-2679 v4 @ 2.50GHz comes with a CPU mark of 25236 and will be able to handle 7010 viewers at the same time.

Memory (RAM)

Memory gets some heavier use for media servers as memory is often used for temporary files such as stream data itself. This means it is often used for both incoming and outgoing streams and the required memory can raise quite rapidly. MistServer tries to get a handle on this by sharing the stream data between inputs, outputs and even different protocols when possible. Still, safest is to calculate the necessary memory for the absolute worst case scenario where memory cannot be shared at all!

To calculate the memory use in the worst case scenario when using MistServer you will require memory per viewer and the amount depends on the quality of your stream. MistServer needs roughly 12.5MB for every megabit of incoming stream bandwidth under the default MistServer settings. So obviously the more streams or stream tracks the more memory you need. On top of this comes a constant 2MB of memory necessary per active connection (either direction).

So if I assume 50 incoming streams of 2mbps and 600 viewers I will need: 12.5×2×50 = 725 MB + 2×650 = 2025MB. So roughly 2GB, now I would recommend a safety margin of at least 10% so going with at least 2.2GB would be wise.

Bandwidth (network)

Bandwidth is often the main bottleneck when it comes to streaming media, especially when higher qualities like 4K are used. Bandwidth is simply the amount of traffic your server can handle before the network connection is saturated. Once your network gets saturated it will mean users will have to wait for their data which often leads to a very bad viewer experience when it comes to media. So it is definitely one of the main things to avoid and thus necessary to calculate what you can handle.

Luckily this is quite easy to calculate, all you need is to know the stream quality and multiply this by every connection (both incoming and outgoing) for every stream you have or plan to have and add it together. Do note that even if a stream quality or stream itself is not viewed the incoming connection will still use up network bandwidth if it is pushed from an outside source, so do not neglect those streams.

For example if I got 6 streams, one of 1mbps, two of 2mbps and 2 of 5mbps with 50 viewers on the 1mbps, 300 viewers on 2mbps and 150 viewers on 5mbps I will need to be able to handle: 1mbps×(50+1)+2mbps×(300+2)+5mbps×(150+3) = 1568mbps. As you can see especially higher quality streams can cause this to raise rather fast, which is usually why a CDN or load balancer is used.

Storage (disk)

Storage is usually more easily understood, all you need is enough space to fit whatever streams you want to provide on demand or record. Especially with the price of storage compared to the other hardware requirements people tend to go a bit too far with their storage. It cannot hurt to have more though.

Storage is easily calculated, all you need to do is multiply the stream quality by the duration for every stream you have. The only thing you will want to pay attention to is that stream qualities are measured in bits while storage is measured in bytes. There are 8 bits in a byte, so the storage necessary is 8 times less than the bandwidth×duration.

Following the example of bandwidth if I got the same 6 streams, one of 1mbps and two of 2mbps and 5mbps and would want to record those all for 20 minutes I would need: (1×20×60+2×2×20×60+5×2×20×60) / 8 = 2250MB. So you would need a little over 2GB.

Calculate your own hardware requirements

Below are a few calculators that you can fill in to calculate your own bandwidth requirements, or server capacity for your current system and again they are meant for calculating your hardware requirements with MistServer so do not expect the same requirements with other media servers.

Hardware requirements calculator for MistServer

Server capacity calculator for MistServer

Formulas to manually calculate

If you'd rather calculate by hand that's possible too. Just use the following formulas:

  • CPU: 3.4×connections(viewers + incoming streams) = necessary cpubenchmark score
  • Memory: 12.5×Stream_mbps×Streams_total + 2*Viewers = MB RAM
  • Bandwidth: Average_stream_quality_mbps×(Input_streams + Viewers) = Bandwidth in Mbit
  • Storage: Total_duration_of_recordings×Average_stream_quality_mbps / 8 = Storage in MByte

As a reminder the steps between kilo, mega and giga are 1024 not 1000 when we're measuring bits or bytes. So make sure you use 1024 when changing between the values or you will have a calculation error.

Well that was it for this blog post, I hope it helped you understand what kind of hardware you will need to search for when using MistServer. Our next blogpost will be done by Erik and will handle stream encryption.