> On June 10, 2014, 1:22 a.m., Ben Mahler wrote: > > Please do a grep for 'quorum', I believe there are a few other places that > > need to be modified (mesos-local and tests). > > > > What if both flags are specified? We should either reject this or validate > > the values (e.g. quorum=1 masters=3 is not safe, quorum=4 masters=3 is > > invalid). > > Chengwei Yang wrote: > I see, there is another bug in auto initialization code, which get > clusterSize as quorum * 2 - 1, this is not correct, say below examples. > > num-masters quorum clusterSize > 1 1 1 > 2 2 3 (wrong) > 3 2 3 > 4 3 5 (wrong) > 5 3 5 > ... > > So need more changes to code. I'd like to describe my idea before submit > a new version of patch. > > 1. since 0.19.0 is freezing, this patch will go 0.20.x > > There are two options I'd like to hear from you. > > 1. --num_masters will replace --quorum, means overwrite --quorum for > several releases and finally remove '--quorum', so no non-standard quorum > will be used. quorum = num_master / 2 + 1 > 2. both --num_masters and --quorum are used, user can specify > non-standard quorum if he like, specify a larger quorum may introduce > performance regression while a smaller quorum may introduce inconsistency. > > Generally, I vote the first option, how do you think?
I think it would be nice to get to your suggestion (2): --num_masters (required) --quorum (optional, for those looking for stronger replication at the cost of performance) If we pass in --num_masters to the log code as the clusterSize, is there anything you don't like about this option? How about the following phased transition: 0.20.0: At least one of --quorum or --num_masters is required. This lets those using --quorum upgrade without effort and allows them to add --num_masters while running this version. We pass --num_masters to the relevant log initialization code. 0.21.0: --num_masters (required), --quorum (optional) How does that sound to you? - Ben ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: https://reviews.apache.org/r/22369/#review45186 ----------------------------------------------------------- On June 10, 2014, 1:03 a.m., Chengwei Yang wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://reviews.apache.org/r/22369/ > ----------------------------------------------------------- > > (Updated June 10, 2014, 1:03 a.m.) > > > Review request for mesos. > > > Bugs: https://issues.apache.org/jira/browse/MESOS-1465 > > https://issues.apache.org/jira/browse/https://issues.apache.org/jira/browse/MESOS-1465 > > > Repository: mesos-git > > > Description > ------- > > Use '--nr_of_masters' instead of '--quorum' because user may confused > with zookeeper quorum and may specify an incorrect quorum if he/she > doesn't know quorum well. > > Use '--nr_of_masters' just simple and straight-forward, and quorum will > be nr_of_masters / 2 + 1, since specify a larger quorum doesn't make > sense in pratice. > > Review: https://reviews.apache.org/r/22369 > > > Diffs > ----- > > src/master/flags.hpp 4863359 > src/master/main.cpp 8ceaae6 > > Diff: https://reviews.apache.org/r/22369/diff/ > > > Testing > ------- > > done. > > > Thanks, > > Chengwei Yang > >
