HI Carlos, https://github.com/apache/couchdb/blob/f4c6113808d1809469df9c8be9d2f83ef399f064/src/mem3/src/mem3_httpd.erl#L22-L29
nodes() returns all visible nodes that Erlang is aware of, based on the native Erlang clustering functionality. You might have nodes in your Erlang distribution cluster that are not CouchDB nodes, such as operator consoles or other Erlang OTP applications. mem3:nodes() returns all nodes participating in the CouchDB cluster. -Joan ----- Original Message ----- From: "Carlos Alonso" <carlos.alo...@cabify.com> To: "user" <user@couchdb.apache.org> Sent: Thursday, 29 June, 2017 4:48:46 AM Subject: Re: Questions about _membership response meaning Hi guys, just trying to bring this to the top again... To summarise my questions... What does exactly mean for a server to be part of all_nodes and cluster_nodes of the _membership response? Which actions are allowed for it on each situation? Thanks! On Mon, Jun 19, 2017 at 6:25 PM Carlos Alonso <carlos.alo...@cabify.com> wrote: > Hi guys. > > Moving forward with understanding how CouchDB works when working as a > cluster I've reached the add/remove nodes step and I've seen the following > situations in which I'd like to know what do them mean and if there's > something to take care to avoid errors or unexpected behaviours. > > First situation: Having a cluster of 4 nodes, all up and connected (i.e: > they both appear in the all_nodes and cluster_nodes sections of the > _membership endpoint's response), if I ask for any of them to be deleted > (issuing a DELETE against the /_nodes database with its id), it is removed > from the cluster_nodes section and the cluster seems to be working, > possibly because it can still achieve consistency. Is this situation > something considered? What does it exactly mean to be part of all_nodes but > not cluster_nodes? > > Second one: Having same setup as above, I bring down a node and then issue > the DELETE request to have it removed both from all_nodes and cluster_nodes > sections. If I then bring the node up again it automatically appears on the > all_nodes section. It only happens if the disk is still available (i.e, all > data it used to have), if I completely replace the disk with a new, empty > one, when I bring it online it does nothing and I have to ask the cluster > to join it by running a PUT request against the /_nodes db. I understand > that some information is persisted into disk that allows it to > automatically join the cluster. > > I'd like to have a clearer picture of what it means to appear in the > all_nodes and cluster_nodes and each situation's considerations as I can't > find it documented anywhere. (i.e, if in all_nodes but not in cluster_nodes > it means it cannot...). > > Thanks! > -- > [image: Cabify - Your private Driver] <http://www.cabify.com/> > > *Carlos Alonso* > Data Engineer > Madrid, Spain > > carlos.alo...@cabify.com > > Prueba gratis con este código > #CARLOSA6319 <https://cabify.com/i/carlosa6319> > [image: Facebook] <http://cbify.com/fb_ES>[image: Twitter] > <http://cbify.com/tw_ES>[image: Instagram] <http://cbify.com/in_ES>[image: > Linkedin] <https://www.linkedin.com/in/mrcalonso> > -- [image: Cabify - Your private Driver] <http://www.cabify.com/> *Carlos Alonso* Data Engineer Madrid, Spain carlos.alo...@cabify.com Prueba gratis con este código #CARLOSA6319 <https://cabify.com/i/carlosa6319> [image: Facebook] <http://cbify.com/fb_ES>[image: Twitter] <http://cbify.com/tw_ES>[image: Instagram] <http://cbify.com/in_ES>[image: Linkedin] <https://www.linkedin.com/in/mrcalonso> -- Este mensaje y cualquier archivo adjunto va dirigido exclusivamente a su destinatario, pudiendo contener información confidencial sometida a secreto profesional. No está permitida su reproducción o distribución sin la autorización expresa de Cabify. Si usted no es el destinatario final por favor elimínelo e infórmenos por esta vía. This message and any attached file are intended exclusively for the addressee, and it may be confidential. You are not allowed to copy or disclose it without Cabify's prior written authorization. If you are not the intended recipient please delete it from your system and notify us by e-mail.
