[VTS] Liveness score is not as precise as we would like to

[onmax]

The current specification only takes two states into account when calculating the liveness score: producing blocks and not producing blocks. offline and online

This is counterintuitive, since the metric we want to measure is the uptime of the server. Since there is no way of knowing whether a server is online or not, the only thing we can know is whether the validator has produced blocks when it should have done so.

If we had a way to know exactly whether validators were online/offline, given a timestamp, a more accurate "liveness" score could be used, and we could even use the name "uptime" instead of "liveness".

We have already discussed this as a team and decided to move forward with this decision. But we decided to leave it here in the discussion for reference.

Small note: You could argue that "uptime" and "reliability" measure the same thing, but that's not quite true:

• Liveness: To know whether the validator is online most of the time, otherwise it will be penalised.
• Reliability: to know if the validator behaves well once selected.

[sisou]

So this is confusing. Checking for block production is for reliability. The documentation says that liveness only comes from being elected vs not elected, nothing about producing blocks. So which one is it, e.g. in the heading of this thread?