It’s the same protection, really, just a matter of flexibility. With 4+2 EC, 7+ hosts are ideal for multiple reasons. You would likely be fine with 6 hosts, so long as you have the ability to quickly repair a host if/when it fails.
> On Apr 22, 2025, at 12:03 PM, gagan tiwari <gagan.tiw...@mathisys-india.com> > wrote: > > Hi Janne, > Thanks for your advice. > > So, you mean with with K=4 M =2 EC, we need 8 OSD nodes to have better > protection > > Thanks, > Gagan > > > > On Tue, 22 Apr, 2025, 7:22 pm Janne Johansson, <icepic...@gmail.com> wrote: > >>> So, I need to know what will be data safely level with the above set-up ( >>> i.e. 6 OSDs with 4X2 EC ). How many OSDs ( disks ) and nodes failure , >>> above set-up can withstand. >> >> With EC N+2 you can lose one drive or host, and the cluster will go on >> with degraded mode until it has been able to recreate the missing data >> on another OSD, if you lose two drives or hosts, I believe the EC pool >> with go readonly, again until it has rebuilt copies elsewhere. >> >> Still, if you have EC 4+2 and only 6 OSD hosts, this means if a host >> dies, the cluster can not recreate data anywhere without violating >> "one copy per host" default placement, so the cluster will be degraded >> until this host comes back or another one replaces it. For a N+M EC >> cluster, I would suggest having N+M+1 or even +2 number of hosts, so >> that you can do maintenance on a host or lose a host and still be able >> to recover without visiting the server room. >> >> -- >> May the most significant bit of your life be positive. >> > _______________________________________________ > ceph-users mailing list -- ceph-users@ceph.io > To unsubscribe send an email to ceph-users-le...@ceph.io _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io
