4 ms·
That's calculated with the assumption that you can cluster the events within a 1-month period and that the events happen at a fixed rate. We are talking about
by emerongi 7y ago
That's calculated with the assumption that you can cluster the events within a 1-month period and that the events happen at a fixed rate.
We are talking about a period of a few days here and about only a handful of services that tout 99.999(9)% uptime. I'm no mathematician but I don't think it's a great comparison.
- 3JPLW 7y agoNo the cluster size isn't fixed, nor is the event rate — the clusters are chosen purely based upon what an "unusually long" time between events would be. That's precisely how the rate ends up canceling itself out. Given this formulation, the expected cluster size is always e, regardless of how you define celebrity. That's what makes it fun. Now the human psychology part that this doesn't cover is that typically when you have two or three A-listers die, well, then you start seeing all the B- C- and D-listers that also died in the same period that you would have otherwise ignored.
- deleted 7y ago[deleted]
- emerongi 7y agoCan you calculate the chance of the cluster size being >5 when we can cluster events within a one-week period and the rate of events is one every 2 months (debatable, but feels right to me)? I think that would just end this discussion. I don't know how to calculate that, but my intuition says the resulting chance is low.
- appleiigs 7y agoI don't know how to do the math, but my python simulation says zero. import random service_providers = 20 servers_threshold = 5 up_time_threshold = 0.999**7 # prob down in week years = 20 occurrences = 0 # run sim 10,000 times for i in range(0, 10000): servers_down = False # simulate weeks in 20 years for j in range(1, 52*years): how_many_down_this_week = 0 # run up times for service providers for s in range(0, service_providers): up_time = random.random() if up_time > up_time_threshold: how_many_down_this_week += 1 # did they go down? if how_many_down_this_week > servers_threshold: servers_down = True if servers_down == True: occurrences += 1 print(occurrences)
- joshuamorton 7y agoGiven those parameters, you'd expect to see something every 100,000 years or so. (poisson distribution, lambda=1/8, k=5, the result is like 7e-7).
- desdiv 7y agoAWS averages about one major outage per year[0]. Google's own status page[1] list near 100 incidents in the past 365 days, only one of which ended on HN frontpage. [0] https://en.wikipedia.org/wiki/Timeline_of_Amazon_Web_Services#Amazon_Web_Services_Outages https://en.wikipedia.org/wiki/Timeline_of_Amazon_Web_Service... [1] https://status.cloud.google.com/summary https://status.cloud.google.com/summary
- emerongi 7y agoGood correction: the outages do happen at a fixed rate. Regarding GCP, I only see a couple events that have lasted more than 8 hours, not sure how many of those affect more than one subsystem.
- Buge 7y agoBoth of these Google outages made it to the HN frontpage: https://news.ycombinator.com/item?id=20077421 https://news.ycombinator.com/item?id=20077421 https://news.ycombinator.com/item?id=20338263 https://news.ycombinator.com/item?id=20338263 Both of these AWS outages made it to the HN frontpage (and neither are listed in that AWS timeline): https://news.ycombinator.com/item?id=20298719 https://news.ycombinator.com/item?id=20298719 https://news.ycombinator.com/item?id=19749781 https://news.ycombinator.com/item?id=19749781