Hi Yihao, On 20/07/2018 07:50, Yihao Jia wrote:

Is there a max running measurement number for a user?

I try to launch about 800 measurements, but only about 150 of them succeed and keep running, while another 650 fail with the description "overlimited denied" one of the fail measurement is: https://atlas.ripe.net/measurements/15302198/

There are indeed limits on the number of concurrent measurements, amongst other kinds of limits. They are documented here: https://atlas.ripe.net/docs/udm/#rate-limits It is possible for limits to be temporarily increased to allow people to perform research. If you'd like to email me directly with the outline of your proposed experiment then I should be able to either increase your limits temporarily and/or advise you on using RIPE Atlas more efficiently.

Do you know what's the reason I failed? (btw, I am wondering how to check the reason why a measurement is failed by the measurement id?)

You can see the status of the measurement using the API: https://atlas.ripe.net/api/v2/measurements/15302198/ In this case the status is "Scheduling denied", which is the delayed version of the "overlimited denied" message that you saw with the other measurements. This is because we do an initial check when you POST and a second check when we are about to allocate probes. The other measurement that you mentioned: https://atlas.ripe.net/api/v2/measurements/15282285/ has a status of "Failed". In this case it is probably because the stop time is too close to the time that you scheduled the measurement so it didn't have a chance to run. Try increasing the stop time to a point further in the future. The statuses of measurements are not currently displayed clearly on the web site, but that will be changing in the near future as we are overhauling the measurement details pages. Kind regards, Chris Amin RIPE NCC