I've read the thesis, but not the papers! Didn't even know they existed... I just looked them over, there's a lot of overlap with the thesis, I'm still not sure how everything works. If someone could outline/clarify the process (for example in a numbered list of steps) I would be very grateful. I'll still go over the papers in detail - I just find the papers and thesis a little confusing on this. I'd say the definitive source for this would be the actual code, but I have neither the time nor the experience with C++ to be able to go over it... btw, thanks for the links :P On Mon, Jul 4, 2011 at 20:49, Wido den Hollander <wido@xxxxxxxxx> wrote: > Hi, > > On Mon, 2011-07-04 at 20:17 +0300, Vasilakakos Giorgos wrote: >> Hello folks, I have a question: >> I know files get mapped to objects and those objects to OSDs but how >> exactly do we go from one to the other? >> What I mean is, given the filename I want to access how does Ceph find >> the relevant objects? What exactly does CRUSH do? >> Supposedly, the client first asks the MDS for an inode number, what then? >> How are the object and PG IDs constructed and where exactly does CRUSH come in? >> My impression is that the OID is made from the name, inode and >> probably some kind of information about the striping of the file, >> what about the mapping of an object to a PG? >> Are PGs mapped to OSDs by means of CRUSH, or are objects mapped to PGs >> by CRUSH? How are PGs assigned to OSDs then? >> >> Could someone clarify this part for me? > > Have you read the RADOS, CRUSH and Ceph thesis on the website? > > Try: > * http://ceph.newdream.net/weil-thesis.pdf > * http://ceph.newdream.net/papers/weil-rados-pdsw07.pdf > * http://ceph.newdream.net/papers/weil-ceph-osdi06.pdf > * http://ceph.newdream.net/papers/weil-crush-sc06.pdf > > I think that should cover most of it. > >> >> Thanks in advance >> -- >> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
