I think it's just for service isolation that people recommend splitting them. The only technical issue I can think of is that you don't want to put kernel clients on the same OS as an OSD (due to deadlock scenarios under memory pressure and writeback). -Greg On Sat, Dec 27, 2014 at 12:11 PM Christopher Armstrong <ch...@opdemand.com> wrote:
> Hi folks, > > I've heard several comments on the mailing list warning against running > multiple Ceph services (monitors, daemons, MDS, gateway) on the same > machine. I was wondering if someone could shed more light on the dangers of > this. In Deis[1] we only require clusters to be 3 machines big, and we need > to run monitors, daemons, and MDS servers. Deis runs on CoreOS, so all of > our services are shipped as Docker containers. We run Ceph within > containers as our store[2] component, so on a single CoreOS host we're > running a monitor, daemon, MDS, gateway, and consuming the cluster with a > CephFS mount. > > I know it's ill-advised, but my question is - why? What sort of issues are > we looking at? Data loss, performance, etc.? When I implemented this I was > unaware of the recommendation not to do this, and I'd like to address any > potential issues now. > > Thanks! > > Chris > > [1]: https://github.com/deis/deis > [2]: https://github.com/deis/deis/tree/master/store > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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