Le vendredi 04 juin 2021 à 15:23 +0200, Dominik Csapak a écrit : > On 6/4/21 04:47, aderum...@odiso.com wrote: > > Hi, > > > > > Hi, > > > I was doing a training week with students, > > > > and I see that the new ceph wizard to create pool don't allow to > > set > > min_size=1 anymore. > > > > It's currently displaying a warning "min_size <= size/2 can lead to > > data loss, incomplete PGs or unfound objects", > > > > that's ok , but It's also blocking the validation button. > > > > yes, in our experience, setting min_size to 1 is always a bad idea > and most likely not what you want > > what is possible though is to either create the pool on the cli, > or changing the min_size after creation to 1 (this is not blocked) > yes, Sute. I could be great to be able to change size/min_size from the gui too.
> > > > > > Some users with small cluster/budgets want to do only size=2, > > > > so with min_size=2, the cluster will go read only in case of any > > osd > > down. > > > > It could be great to allow at least min_size=1 when size=2 is used. > > > > "great" but very dangerous > > > > > also, > > Other setup like size=4, min_size=2, also display the warning, but > > allow to validate the form. > > > > I'm not sure this warning is correct in this case , as since > > octopus, > > min_size > > is auto compute when pool is created, and a simple > > > > ceph osd pool create mypool 128 --size=4 , create a pool with > > min_size=2 by default. > > > > > > the rationale behind this decision was (i think) because > if you have exactly 50% min_size of size (e.g. 4/2) > you can get inconsistent pgs, with no quorum as to > which pg is correct? > (though don't quote me on that) > > so i think its always better to have > 50% min_size of size > Well, afaik, they are no "quorum" on pg consistency for repair currently. if a pg is corrupt, ceph is simply copy data from a pg copy where checksum is ok. and if no checksum is available, it take a random copy. (maybe it need a manual pg_repair in this case). But They are not something like "theses 2 copies have the more majority (quorum) of checksum. (Maybe I'm wrong, but 1 or 2 year ago, Sage have confirmed this on the ceph mailing) _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel
