On Thu, Mar 29, 2018 at 12:25 PM, Janne Johansson <icepic...@gmail.com> wrote:
> > > 2018-03-29 11:50 GMT+02:00 David Rabel <ra...@b1-systems.de>: > >> On 29.03.2018 11:43, Janne Johansson wrote: >> > 2018-03-29 11:39 GMT+02:00 David Rabel <ra...@b1-systems.de>: >> > >> >> For example a replicated pool with size 4: Do i always have to set the >> >> min_size to 3? Or is there a way to use min_size 2 and use some other >> >> node as a decision maker in case of split brain? >> >> >> > >> > min_size doesn't arbitrate decisions other than >> > "can I write if there are only X visible copies?", where X needs to be > >> > min_size >> > to allow writes. >> > I think X >= allows IO to data pool > > >> > It doesn't control any logic, it controls the risk level you want to >> take. >> >> You are right. But with my above example: If I have min_size 2 and size >> 4, and because of a network issue the 4 OSDs are split into 2 and 2, is >> it possible that I have write operations on both sides and therefore >> have inconsistent data? >> > > You always write to the primary, which in turn sends copies to the 3 > others, > so in the 2+2 split case, only one side can talk to the primary OSD for > that pg, > so writes will just happen on one side at most. > Could be that your OSDs will be marked as DOWN, see http://docs.ceph.com/docs/master/rados/configuration/mon-osd-interaction/#osds-check-heartbeats Regarding MON split see http://lists.ceph.com/pipermail/ceph-users-ceph.com/2018-March/025756.html > > > -- > May the most significant bit of your life be positive. > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > >
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