A patch to the setup wizard and _cluster_setup endpoint would also work, if it included the advice here, which I mainly agree with.
There is some variance on how many couchjs process are expected, but other than that, this looks like not bad advice. > On 11. Jul 2019, at 18:07, Joan Touzet <woh...@apache.org> wrote: > > Hi Tabeth, > > This is a good start. I'll let others comment on the specific advice. > > One point raised in this thread is ermouth's request to have this value > automatically set by the installer. Detecting the number of cores in a > cross-platform way is pretty challenging, especially when you consider > things like hyperthreading (which aren't full "cores") on physical machines. > > I agree a table would be a good thing for the docs, but we really need a > single number for q (plus other config settings) that will be good > defaults for low-performing HW. > > -Joan > > On 2019-07-11 11:43, Tabeth Nkangoh wrote: >> Hello all, >> >> >> After reading the documentation >> <https://docs.couchdb.org/en/2.2.0/cluster/sharding.html> and this thread I >> propose the following formula to document officially for determining the Q >> and N values. >> >> >> To start, as currently documented, N should be set to the number of nodes. >> This much is straightforward and is documented more or less correctly. >> >> >> >> For Q, it should equal the amount of cores at a minimum. So, for the >> cheapest Digital Ocean droplet, which 1GB of RAM and 1vCPU, Q should be set >> to 1 by the user. In the case that each core is sufficiently beefy, e.g. >> Intel Xeon or turbo clocked AMD EPYC 7000 2 should be added. 2 is an >> arbitrary value but reflects the reality that from what I can tell a >> dramatically higher clock speed benefits CouchDB performance AFAIK (I'm not >> sure if this benefit is a constant or a multiplier, but I doubt it is a >> multiplier simply due to the diminishing returns seen in increased clock >> speed). >> >> >> To summarize the following table can be used (for example): >> >> >> CPU Cores CPU Clock Speed Q Value >> 1 Low 1 >> 2 Low 2 >> 2 High 4 >> 3 High 5 >> 4 Low 4 >> >> >> Does anyone have any qualms with this as a general guide to give users in >> determining the Q value they should set for their CouchDB instance? If not I >> can submit a PR soon on this (have to figure out how to create a new >> reference for one that's currently open first). >> >> Tabeth >> >> ________________________________ >> From: Joan Touzet <woh...@apache.org> >> Sent: Thursday, July 11, 2019 11:17 AM >> To: dev@couchdb.apache.org >> Subject: Re: CouchDB and future >> >> 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 >> >> > -- Professional Support for Apache CouchDB: https://neighbourhood.ie/couchdb-support/
