Bryan Henderson <bry...@giraffe-data.com> 于 2018年6月2日周六 10:23写道：
> >Luckily; it's not. I don't remember if the MDS maps contain entirely > >ephemeral data, but on the scale of cephfs recovery scenarios that's just > >about the easiest one. Somebody would have to walk through it; you > probably > >need to look up the table states and mds counts from the RADOS store and > >generate a new (epoch 1 or 2) mdsmap which contains those settings ready > to > >go. Or maybe you just need to "create" a new cephfs on the prior pools and > >set it up with the correct number of MDSes. > > > >At the moment the mostly-documented recovery procedure probably involves > >recovering the journals, flushing everything out, and resetting the server > >state to a single MDS, and if you lose all your monitors there's a good > >chance you need to be going through recovery anyway, so...*shrug* > > The idea of just creating a new filesystem from old metadata and data pools > intrigued me, so I looked into it further, including reading some code. > > It appears that there's nothing in the MDS map that can't be regenerated, > and > while it's probably easy for a Ceph developer to do that, there aren't > tools > available that can. > > 'fs new' comes close, but according to > > http://docs.ceph.com/docs/master/cephfs/disaster-recovery/ > > it causes a new empty root directory to be created, so you lose access to > all > your files (and leak all the storage space they occupy) > Kill all mds first , create new fs with old pools , then run ‘fs reset’ before start any MDS. > The same document mentions 'fs reset', which also comes close and keeps the > existing root directory, but it requires, perhaps gratuitously, that a > filesystem already exist in the MDS map, albeit maybe corrupted, before it > regenerates it. > > I'm tempted to modify Ceph to try to add a 'fs recreate' that does what 'fs > reset' does, but without expecting anything to be there already. Maybe > that's > all it takes along with 'ceph-objecstore-tool --op update-mon-db' to > recover > from a lost cluster map. > > -- > Bryan Henderson San Jose, California > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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