> -----Message d'origine----- > De : Wido den Hollander [mailto:w...@42on.com] > Envoyé : mercredi 7 décembre 2016 16:01 > À : ceph-us...@ceph.com; LOIC DEVULDER - U329683 <loic.devul...@mpsa.com> > Objet : RE: [ceph-users] 2x replication: A BIG warning > > > > Op 7 december 2016 om 15:54 schreef LOIC DEVULDER > <loic.devul...@mpsa.com>: > > > > > > Hi Wido, > > > > > As a Ceph consultant I get numerous calls throughout the year to > > > help people with getting their broken Ceph clusters back online. > > > > > > The causes of downtime vary vastly, but one of the biggest causes is > > > that people use replication 2x. size = 2, min_size = 1. > > > > We are building a Ceph cluster for our OpenStack and for data integrity > reasons we have chosen to set size=3. But we want to continue to access > data if 2 of our 3 osd server are dead, so we decided to set min_size=1. > > > > Is it a (very) bad idea? > > > > I would say so. Yes, downtime is annoying on your cloud, but data loss if > even worse, much more worse. > > I would always run with min_size = 2 and manually switch to min_size = 1 > if the situation really requires it at that moment. > > Loosing two disks at the same time is something which doesn't happen that > much, but if it happens you don't want to modify any data on the only copy > which you still have left. > > Setting min_size to 1 should be a manual action imho when size = 3 and you > loose two copies. In that case YOU decide at that moment if it is the > right course of action. > > Wido
Thanks for your quick response! That's make sense, I will try to convince my colleagues :-) Loic _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
