On Tue, Sep 29, 2015 at 7:24 AM, Andras Pataki <apat...@simonsfoundation.org> wrote: > Thanks, that makes a lot of sense. > One more question about checksumming objects in rados. Our cluster uses > two copies per object, and I have some where the checkums mismatch between > the two copies (that deep scrub warns about). Does ceph store an > authoritative checksum of what the block should look like? I.e. Is there > a way to tell which version of the block is correct? I seem to recall > some changelog entry that Hammer is adding checksum storage for blocks, or > am I wrong?
There's no general authoritative checksumming yet. EC pools get checksums, and replicated pools checksum the objects as part of deep scrub. But maintaining a checksum when you do a partial overwrite requires reading the whole object and updating the checksum, so we don't do that. NewStore is doing some stuff like this (but I'm not sure how much you can count on) and there is "opportunistic checksumming" in the code base, but that's really just a developer feature rather than something users should be running. So that means there's no automated way to guarantee the right copy of an object when scrubbing. If you have 3+ copies I'd recommend checking each of them and picking the one that's duplicated... -Greg > > Andras > > > On 9/29/15, 9:58 AM, "Gregory Farnum" <gfar...@redhat.com> wrote: > >>The formula for objects in a file is <ino in hex>.<object in >>sequence>. So you'll have noticed they all look something like >>12345.00000001, 12345.00000002, 12345.00000003, ... >> >>So if you've got a particular inode and file size, you can generate a >>list of all the possible objects in it. To find the object->OSD >>mapping you'd need to run crush, by making use of the crushtool or >>similar. >>-Greg >> >>On Tue, Sep 29, 2015 at 6:29 AM, Andras Pataki >><apat...@simonsfoundation.org> wrote: >>> Thanks, that worked. Is there a mapping in the other direction easily >>> available, I.e. To find where all the 4MB pieces of a file are? >>> >>> On 9/28/15, 4:56 PM, "John Spray" <jsp...@redhat.com> wrote: >>> >>>>On Mon, Sep 28, 2015 at 9:46 PM, Andras Pataki >>>><apat...@simonsfoundation.org> wrote: >>>>> Hi, >>>>> >>>>> Is there a way to find out which radios objects a file in cephfs is >>>>>mapped >>>>> to from the command line? Or vice versa, which file a particular >>>>>radios >>>>> object belongs to? >>>> >>>>The part of the object name before the period is the inode number (in >>>>hex). >>>> >>>>John >>>> >>>>> Our ceph cluster has some inconsistencies/corruptions and I am trying >>>>>to >>>>> find out which files are impacted in cephfs. >>>>> >>>>> Thanks, >>>>> >>>>> Andras >>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> ceph-users mailing list >>>>> ceph-users@lists.ceph.com >>>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>>>> >>> >>> _______________________________________________ >>> ceph-users mailing list >>> ceph-users@lists.ceph.com >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
