You can reduce min_size to k in an ec pool. But that's a very bad idea for the same reason that min_size 1 on a replicated pool is bad. Paul -- Paul Emmerich Looking for help with your Ceph cluster? Contact us at https://croit.io croit GmbH Freseniusstr. 31h 81247 München www.croit.io Tel: +49 89 1896585 90 On Wed, Feb 20, 2019 at 11:27 AM Eugen Block <eblock@xxxxxx> wrote: > > Hi, > > I see that as a security feature ;-) > You can prevent data loss if k chunks are intact, but you don't want > to work with the least required amount of chunks. In a disaster > scenario you can reduce min_size to k temporarily, but the main goal > should always be to get the OSDs back up. > For example, in a replicated pool with size 3 we set min_size to 2 not > to 1, although that would also work if everything is healthy. But it's > risky since there's also a chance that two corrupt PGs overwrite a > healthy PG. > > Regards, > Eugen > > > Zitat von "Clausen, Jörn" <jclausen@xxxxxxxxx>: > > > Hi! > > > > While trying to understand erasure coded pools, I would have > > expected that "min_size" of a pool is equal to the "K" parameter. > > But it turns out, that it is always K+1. > > > > Isn't the description of erasure coding misleading then? In a K+M > > setup, I would expect to be good (in the sense of "no service > > impact"), even if M OSDs are lost. But in reality, my clients would > > already experience an impact when M-1 OSDs are lost. This means, you > > should always consider one more spare than you would do in e.g. a > > classic RAID setup, right? > > > > Joern > > > > -- > > Jörn Clausen > > Daten- und Rechenzentrum > > GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel > > Düsternbrookerweg 20 > > 24105 Kiel > > > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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