In my effort to learn more of the details of Ceph, I'm trying to figure out how to get from an object name in RadosGW, through the layers, down to the files on disk. clewis at clewis-mac ~ $ s3cmd ls s3://cpltest/ 2014-08-13 23:02 14M 28dde9db15fdcb5a342493bc81f91151 s3://cpltest/vmware-freebsd-tools.tar.gz Looking at the .rgw pool's contents tells me that the cpltest bucket is default.73886.55: root at dev-ceph0:/var/lib/ceph/osd/ceph-0/current# rados -p .rgw ls | grep cpltest cpltest .bucket.meta.cpltest:default.73886.55 The rados objects that belong to that bucket are: root at dev-ceph0:~# rados -p .rgw.buckets ls | grep default.73886.55 default.73886.55__shadow__RpwwfOt2X-mhwU65Qa1OHDi--4OMGvQ_1 default.73886.55__shadow__RpwwfOt2X-mhwU65Qa1OHDi--4OMGvQ_3 default.73886.55_vmware-freebsd-tools.tar.gz default.73886.55__shadow__RpwwfOt2X-mhwU65Qa1OHDi--4OMGvQ_2 default.73886.55__shadow__RpwwfOt2X-mhwU65Qa1OHDi--4OMGvQ_4 I know those shadow__RpwwfOt2X-mhwU65Qa1OHDi--4OMGvQ_ files are the rest of vmware-freebsd-tools.tar.gz. I can infer that because this bucket only has a single file (and the sum of the sizes matches). With many files, I can't infer the link anymore. How do I look up that link? I tried reading the src/rgw/rgw_rados.cc, but I'm getting lost. My real goal is the reverse. I recently repaired an inconsistent PG. The primary replica had the bad data, so I want to verify that the repaired object is correct. I have a database that stores the SHA256 of every object. If I can get from the filename on disk back to an S3 object, I can verify the file. If it's bad, I can restore from the replicated zone. Aside from today's task, I think it's really handy to understand these low level details. I know it's been handy in the past, when I had disk corruption under my PostgreSQL database. Knowing (and practicing) ahead of time really saved me a lot of downtime then. Thanks for any pointers.
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