On Wed, Oct 16, 2013 at 6:12 PM, Sage Weil <sage@xxxxxxxxxxx> wrote: >> 3. During deep scrub of an object with 2 replicas, suppose the checksum is different for the two objects -- which object wins? (I.e. if you store the checksum locally, this is trivial since the consistency of objects can be evaluated locally. Without the local checksum, you can have conflicts.) > > In this case we normally choose the primary. The repair has to be > explicitly triggered by the admin, however, and there are some options to > control that choice. Which options would those be? I only know about ceph pg repair <pg.id> BTW, I read in a previous mail that... > Repair does the equivalent of a deep-scrub to find problems. This mostly is reading object data/omap/xattr to create checksums and compares them across all copies. When a discrepancy is identified an arbitrary copy which did not have I/O errors is selected and used to re-write the other replicas. This seems like a right thing to do when inconsistencies are the result of i/o errors. But when caused by random bit flips, this sounds like an effective way to propagate corrupted data while making ceph health = HEALTH_OK. Is that opportunistic checksum feature planned for emporer? Cheers, Dan _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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