Witnesses following the old setup guides, especially newbies, should know that the server specs get obsolete as time goes by. For instance, when I started my server 3 months ago, the RAM recommendation was 12 GB. At that time, the steem daemon was using around 7 GB. Today, as I'm writing this post, the memory usage is 12.2 GB! That's a whopping 5.2 GB increase, i.e. 1.7 GB/month. At this rate, in less than two months, we will cross the 16 GB threshold. If your system has 16 GB RAM, consider upgrading it before it's too late.
Witnesses (newbies and non-newbies!) who comfortably set their shared memory file to 12 GB, experienced many missed blocks recently, because of memory overflows.
My advice is to often check your memory usage with htop for example (you can install it with: sudo apt install htop). Here's an example of htop output on my main server:
Pay attention to the 'Mem' value, which reflects the total RAM usage, and the RES column of the steemd process, which is its RAM usage.
So, my main server is using 12.7 GB of RAM, out of which 12.2 GB is used by steemd. The values can vary from one system to another, and depends on the plugins you have loaded. However, a witness running only the witness plugin should have similar figures.
So the things to watch out for are:
- Total RAM usage of your system
- The shared-file-size set in the config.ini
- The shared memory file size set with
./run.sh shm_sizecommand if you're using's dockerized setup.
To avoid problems, set the shared-file-size value to be equal (never exceed) to the shared memory file, and both be slightly less than your total RAM. For example, on a 16 GB system (actually 15.7 G), set your values to 15 G.
And it goes without saying, if you are producing many blocks daily, have a fail-over or a kill switch mechanism to minimize missed blocks when something goes wrong.
For a seed node, the memory usage is currently around 9.5 GB, so there's more buffer there before anything goes wrong.
Check this guide on HTOP http://www.deonsworld.co.za/2012/12/20/understanding-and-using-htop-monitor-system-resources/
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