Re: [ceph-users] Two mons
Thanks a lot Greg, nice to hear! 2017-08-15 21:17 GMT+02:00 Gregory Farnum : > On Tue, Aug 15, 2017 at 10:28 AM David Turner > wrote: > >> There is nothing that will stop you from having an even number of mons >> (including 2). You just run the chance of getting into a split brain >> scenario. >> > > Just a note: even numbers of monitors mean that it's easier to lose > quorums, but they cannot create a classic split brain (in which two sets of > monitors both think they are in charge). We work very hard to avoid that > situation ever arising in RADOS. :) > -Greg > > > As long as you aren't planning to stay in that scenario, I don't see a >> problem with it. I have 3 mons in my home cluster and I've had to remove >> one before leaving me with 2 for a few hours while I re-provisioned the >> third and nothing funky happened. >> >> Most ways to deploy a cluster allow you to create the cluster with 3+ >> mons at the same time (inital_mons). What are you doing that only allows >> you to add one at a time? >> >> On Tue, Aug 15, 2017 at 12:22 PM Oscar Segarra >> wrote: >> >>> Hi, >>> >>> I'd like to test and script the adding monitors process adding one by >>> one monitors to the ceph infrastructure. >>> >>> Is it possible to have two mon's running on two servers (one mon each) >>> --> I can assume that mon quorum won't be reached until both servers are up. >>> >>> Is this right? >>> >>> I have not been able to find any documentation about the behaviour of >>> the sistem with just two monitors (or an even number of them). >>> >>> thanks a lot. >>> ___ >>> ceph-users mailing list >>> ceph-users@lists.ceph.com >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>> >> ___ >> ceph-users mailing list >> ceph-users@lists.ceph.com >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> > ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
Re: [ceph-users] Two mons
On Tue, Aug 15, 2017 at 10:28 AM David Turner wrote: > There is nothing that will stop you from having an even number of mons > (including 2). You just run the chance of getting into a split brain > scenario. > Just a note: even numbers of monitors mean that it's easier to lose quorums, but they cannot create a classic split brain (in which two sets of monitors both think they are in charge). We work very hard to avoid that situation ever arising in RADOS. :) -Greg As long as you aren't planning to stay in that scenario, I don't see a > problem with it. I have 3 mons in my home cluster and I've had to remove > one before leaving me with 2 for a few hours while I re-provisioned the > third and nothing funky happened. > > Most ways to deploy a cluster allow you to create the cluster with 3+ mons > at the same time (inital_mons). What are you doing that only allows you to > add one at a time? > > On Tue, Aug 15, 2017 at 12:22 PM Oscar Segarra > wrote: > >> Hi, >> >> I'd like to test and script the adding monitors process adding one by one >> monitors to the ceph infrastructure. >> >> Is it possible to have two mon's running on two servers (one mon each) >> --> I can assume that mon quorum won't be reached until both servers are up. >> >> Is this right? >> >> I have not been able to find any documentation about the behaviour of the >> sistem with just two monitors (or an even number of them). >> >> thanks a lot. >> ___ >> ceph-users mailing list >> ceph-users@lists.ceph.com >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> > ___ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
Re: [ceph-users] Two mons
Hi David, Thanks a lot for your quick response... *What are you doing that only allows you to add one at a time?* I'm trying to create a scrip for adding/removing a mon in my environment --> I want to execute it from a simple web page... Thanks a lot! 2017-08-15 19:26 GMT+02:00 David Turner : > There is nothing that will stop you from having an even number of mons > (including 2). You just run the chance of getting into a split brain > scenario. As long as you aren't planning to stay in that scenario, I don't > see a problem with it. I have 3 mons in my home cluster and I've had to > remove one before leaving me with 2 for a few hours while I re-provisioned > the third and nothing funky happened. > > Most ways to deploy a cluster allow you to create the cluster with 3+ mons > at the same time (inital_mons). What are you doing that only allows you to > add one at a time? > > On Tue, Aug 15, 2017 at 12:22 PM Oscar Segarra > wrote: > >> Hi, >> >> I'd like to test and script the adding monitors process adding one by one >> monitors to the ceph infrastructure. >> >> Is it possible to have two mon's running on two servers (one mon each) >> --> I can assume that mon quorum won't be reached until both servers are up. >> >> Is this right? >> >> I have not been able to find any documentation about the behaviour of the >> sistem with just two monitors (or an even number of them). >> >> thanks a lot. >> ___ >> ceph-users mailing list >> ceph-users@lists.ceph.com >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> > ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
Re: [ceph-users] Two mons
There is nothing that will stop you from having an even number of mons (including 2). You just run the chance of getting into a split brain scenario. As long as you aren't planning to stay in that scenario, I don't see a problem with it. I have 3 mons in my home cluster and I've had to remove one before leaving me with 2 for a few hours while I re-provisioned the third and nothing funky happened. Most ways to deploy a cluster allow you to create the cluster with 3+ mons at the same time (inital_mons). What are you doing that only allows you to add one at a time? On Tue, Aug 15, 2017 at 12:22 PM Oscar Segarra wrote: > Hi, > > I'd like to test and script the adding monitors process adding one by one > monitors to the ceph infrastructure. > > Is it possible to have two mon's running on two servers (one mon each) --> > I can assume that mon quorum won't be reached until both servers are up. > > Is this right? > > I have not been able to find any documentation about the behaviour of the > sistem with just two monitors (or an even number of them). > > thanks a lot. > ___ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
[ceph-users] Two mons
Hi, I'd like to test and script the adding monitors process adding one by one monitors to the ceph infrastructure. Is it possible to have two mon's running on two servers (one mon each) --> I can assume that mon quorum won't be reached until both servers are up. Is this right? I have not been able to find any documentation about the behaviour of the sistem with just two monitors (or an even number of them). thanks a lot. ___ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
