Not even that. :) If you have one node, then your dbs are N=1 even if N is set to 3 in config. the code takes the lower of the n setting and the number of known nodes (which don't have to be up at the time of db creation).
B. > On 5 Oct 2019, at 21:00, Joan Touzet <woh...@apache.org> wrote: > > Agree - couldn't find the reference from earlier, but I believe the > rules should be: > > If you have 1 node, set n=1. > If you have 2 nodes, set n=2. > If you have 3 or more nodes, set n=3. > > Anything else is a special case and isn't recommended. > > -Joan > > On 2019-10-05 15:20, Robert Samuel Newson wrote: >> Pulling this sentence out from much earlier in the thread; >> >> "N should be set to the number of nodes." >> >> That's not true and our docs should not say it today or be changed to say it >> in the future. >> >> N is how many copies of a document we'll maintain. If you had a 20 node >> cluster, you would not want 20 copies of every document. The default of 3 >> copies would be sufficient to prevent accidental loss. >> >> B. >> >>> On 4 Oct 2019, at 23:55, Joan Touzet <woh...@apache.org> wrote: >>> >>> Thanks for the follow-up. Thinking of >1 active DB per host makes this >>> calculation a lot more challenging. >>> >>> Sounds like our recently merged default change of q=2 will be fine. >>> >>> -Joan >>> >>> >>> On 2019-10-04 17:40, ermouth wrote: >>>> This tuned out to be interesting, results vary heavily for different >>>> platforms. >>>> >>>> I included `perftest.html` into Photon design doc. The utility gives good >>>> insight how q,n impact doc creation, doc update, validate + update, and >>>> viewindex create/update – for a particular CouchDB instance. >>>> >>>> Common observations: >>>> * q=1 is only ok for rare special cases (like DBs with dozen docs) >>>> * it’s ok to have q==cores or q==cores+1 or even cores+2: write perf drops >>>> a little, but viewindex update is bit faster >>>> * excessive q (say, more than cores×2) negatively impacts direct write >>>> perf: having q8 for 2core at least halves write perf for most >>>> commodity/lean platforms and hw cfg. >>>> >>>> ermouth >>>> >>>> >>>> чт, 11 июл. 2019 г. в 18:17, Joan Touzet <woh...@apache.org>: >>>> >>>>> On 2019-07-11 8:05, ermouth wrote: >>>>>>> to help with the documentation step >>>>>> >>>>>> Probably. Please give me a hint what you need. >>>>> >>>>> What default settings right now are wrong for a system with low RAM, low >>>>> CPU, and slow disk - such as a RaspberryPi v1, or a $15/mo AWS server? >>>>> >>>>> -Joan >>>>> >>>>> >>>> >>> >> >
