Ziggy, The default min_size for your pool is 3 so losing ANY single OSD (not even host) will result in reduced data availability:
https://patchwork.kernel.org/patch/8546771/ Use m=2 to be able to handle a node failure. Met vriendelijke groet, Caspar Smit Systemengineer SuperNAS Dorsvlegelstraat 13 1445 PA Purmerend t: (+31) 299 410 414 e: caspars...@supernas.eu w: www.supernas.eu 2018-07-20 13:11 GMT+02:00 Ziggy Maes <ziggy.m...@be-mobile.com>: > Hello > > > > I am currently trying to find out if Ceph can sustain the loss of a full > host (containing 4 OSDs) in a default erasure coded pool (k=2, m=1). We > have currently have a production EC pool with the default erasure profile, > but would like to make sure the data on this pool remains accessible even > after one of our hosts fail. Since we have a very small cluster (6 hosts, 4 > OSDs per host), I created a custom CRUSH rule to make sure the 3 chunks are > spread over 3 hosts, screenshot here: https://gyazo.com/ > 1a3ddd6895df0d5e0e425774d2bcb257 . > > > > Unfortunately, taking one node offline results in reduced data > availability and incomplete PGs, as shown here: https://gyazo.com/ > db56d5a52c9de2fd71bf9ae8eb03dbbc . > > > > My question summed up: is it possible to sustain the loss of a host > containing 4 OSDs using a k=2, m=1 erasure profile using a CRUSH map that > spreads data over at least 3 hosts? If so, what am I doing wrong? I realize > the documentation states that m equals the amount of OSDs that can be lost, > but assuming a balanced CRUSH map is used I fail to see how this is > required. > > > > Many thanks in advance. > > > > Kind regards > > > *Ziggy Maes *DevOps Engineer > > [image: http://www.be-mobile.com/mail/bemobile_email.png] > <http://www.be-mobile.com/> > > *www.be-mobile.com <http://www.be-mobile.com>* > > > > > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > >
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