Hi Baptiste, On Wed, Jan 20, 2016 at 11:08 AM, Baptiste <[email protected]> wrote:
> On Sat, Jan 16, 2016 at 3:37 AM, Igor Cicimov > <[email protected]> wrote: > > > > > > On Sat, Jan 16, 2016 at 7:36 AM, Alex <[email protected]> wrote: > >> > >> Hello, > >> > >> I was testing haproxy version 1.6.3 and I am a bit confused regarding > >> draining a server. > >> > >> According to the documentation: > >> set server <backend>/<server> state [ ready | drain | maint ] > >> [...] Setting the mode to "drain" only removes the server from load > >> balancing but still allows it to be checked and to accept new persistent > >> connections. > >> > >> set weight <backend>/<server> <weight>[%] > >> [...] A typical usage of this command is to disable a server during an > >> update by setting its weight to zero, then to enable it again after the > >> update by setting it back to 100%. > >> > >> > > > > Well basically setting weight to 0 immediately disables the backend > > I disagree on this point. Your server will still receive requests with > persistence. > It is simply ejected from the load-balancing algorithm. > Health checks are still performed. > > If this is the case then there isn't any difference between drain and disable in terms of maintenance. Setting the weight to 0 will still allow the exiting sessions to go to the server and get disconnected when the server restarts for update. > whereas draining stops any new connections going to the backend but the > existing > > sessions are allowed to continue until some time limit is reached, lets > say > > 15 minutes, after which the backend gets completely disabled. > > Drain perform the same as above. > I guess checks are also still performed. > > > It is kinda > > removing the backend from the load balancer forcefully vs gracefully > > (allowing the existing sessions to finish). What method to use is really > up > > to you and your user case. > > > > I think you misunderstand "drain" and "disable". Disable forces > everybody to get routed to an other server for their next request. > > Baptiste >
