On 27/10/2015 03:34, Kjetil Babington wrote: > I see, thank you for your replies. I will try to implement a > CRUSH-map, which distributes the chunks in such a way. Do you think > there will be any performance issues with such a map, placing multiple > smaller chunks on each osd instead of one large on each? Maybe but I'd be better able to tell you looking at the crush ruleset. > The reason we would like to do this, is that we have developed some > new erasure codes, which we would like to test on a large-scale > storage system like Ceph. These erasure codes rely on > sub-packetization to reduce the amount of data read from each disk > when reconstructing an erasure. Since CEPH does not seem to have an > ability to read part of a chunk, we thought we could sort of bypass > this by making each chunk contain one sub-packet, and place a set of > these chunks (sub-packets) on each osd. Interesting :-) Could you share the URL to the code of this erasure code plugin ? Cheers > > 2015-10-22 18:59 GMT+02:00 Loic Dachary <loic@xxxxxxxxxxx>: >> Hi, >> >> On 22/10/2015 18:44, Kjetil Babington wrote: >>> Hi, >>> >>> I have a question about the capabilities of the erasure coding API in >>> Ceph. Let's say that I have 10 data disks and 4 parity disks, is it >>> possible to create an erasure coding plugin which creates 20 data >>> chunks and 8 parity chunks, and then places two chunks on each osd? >>> >>> Or said maybe a bit simpler is it possible for two or more chunks from >>> the same encode operation to be placed on the same osd? >> >> This is more a question of creating a crush ruleset that does it. The erasure code plugin encodes chunks but the crush ruleset decides where they are placed. >> >> Cheers >> >>> >>> - Kjetil Babington >>> -- >>> 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 >>> >> >> -- >> Loïc Dachary, Artisan Logiciel Libre >> -- Loïc Dachary, Artisan Logiciel Libre
Attachment:
signature.asc
Description: OpenPGP digital signature
