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Hi Greg Opened this one http://tracker.ceph.com/issues/16567 Let us see what they say. Cheers G. On 07/01/2016 04:09 AM, Gregory Farnum
wrote:
On Wed, Jun 29, 2016 at 10:50 PM, Goncalo Borges <goncalo.borges@xxxxxxxxxxxxx> wrote:Hi ShinobuSorry probably I don't understand your question properly. Is what you're worry about that object mapped to specific pg could be overwritten on different osds?Not really. I was worried by seeing object sizes changing on the fly. I will try to clarify. We are enabling cephfs for our user community. My mind was set to a context where data is not changing. I got scared because I was not finding plausible for the object to change size and content. I thought this was a consequence of a bad repair. However, thinking it over, if we have some application overwritting the same file over and over again (which I think we have), that means that we will see the same objects change size and content over time. In cephfs, the name of the objects is directly related to the file inode and how it is stripped so the object names do not actually change if a file is overwritten. Right?! So, in summary, in this scenario, it is normal for objects to change size and content all the time.That's true...A consequence of this is that the very fast overwrite of files / objects could raise some scrub errors if, by chance, ceph is scrubbing pgs with objects which are changing on the fly....but that's definitely not the case. Scrubbing and client IO shouldn't race with each other. If you're seeing size errors, it could be some minor scrub race, but it's definitely a bug. You should discuss on irc and/or open a ticket for the RADOS team to look at. -Greg -- Goncalo Borges Research Computing ARC Centre of Excellence for Particle Physics at the Terascale School of Physics A28 | University of Sydney, NSW 2006 T: +61 2 93511937 |
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