On 26-03-15 12:04, Stefan Priebe - Profihost AG wrote: > Hi Wido, > Am 26.03.2015 um 11:59 schrieb Wido den Hollander: >> On 26-03-15 11:52, Stefan Priebe - Profihost AG wrote: >>> Hi, >>> >>> in the past i rwad pretty often that it's not a good idea to run ceph >>> and qemu / the hypervisors on the same nodes. >>> >>> But why is this a bad idea? You save space and can better use the >>> ressources you have in the nodes anyway. >>> >> >> Memory pressure during recovery *might* become a problem. If you make >> sure that you don't allocate more then let's say 50% for the guests it >> could work. > > mhm sure? I've never seen problems like that. Currently i ran each ceph > node with 64GB of memory and each hypervisor node with around 512GB to > 1TB RAM while having 48 cores. >
Yes, it can happen. You have machines with enough memory, but if you overprovision the machines it can happen. >> Using cgroups you could also prevent that the OSDs eat up all memory or CPU. > Never seen an OSD doing so crazy things. > Again, it really depends on the available memory and CPU. If you buy big machines for this purpose it probably won't be a problem. > Stefan > >> So technically it could work, but memorey and CPU pressure is something >> which might give you problems. >> >>> Stefan >>> >>> _______________________________________________ >>> ceph-users mailing list >>> ceph-users@lists.ceph.com >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>> >> >> -- Wido den Hollander 42on B.V. Phone: +31 (0)20 700 9902 Skype: contact42on _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
