On Fri, Oct 23, 2015 at 8:17 AM, Stefan Eriksson <ste...@eriksson.cn> wrote: > Hi > > I have been looking for info about "osd pool default size" and the reason > its 3 as default. > > I see it got changed in v0.82 from 2 to 3, > > Here its 2. > http://docs.ceph.com/docs/v0.81/rados/configuration/pool-pg-config-ref/ > > and in v0.82 its 3. > http://docs.ceph.com/docs/v0.82/rados/configuration/pool-pg-config-ref/ > > likewise "osd pool default min size" went from 1 to 1.5 which goes up to 2. > (Default: 0, which means no particular minimum. If 0, minimum is size - > (size / 2).) > > I've looked at the changelog for v0.82 but I cant find the reason for this > change. I'm interested to know why this change was made, I understand 2 is > less secure, but did something change which made it less secure after v0.82? > > It seems pretty ok if you compare it to a RAID5,6 > Openstack users, and other users which host virtual images on ceph, do you > use the default "osd pool default min size = 3"?
Nothing changed to make two copies less secure. 3 copies is just so much more secure and is the number that all the companies providing support recommend, so we changed the default. (If you're using it for data you care about, you should really use 3 copies!) -Greg _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
