Thank you Mike, for your work & answers 2015-12-10 0:37 GMT+03:00 Mike Christie <mchristi@xxxxxxxxxx>: > On 12/09/2015 01:08 AM, Timofey Titovets wrote: >> Hi list, >> As i found write_same_max_bytes are equal to zero >> if i understand correctly, it's means what RBD not support offloading >> copy operations >> > > Not yet. > > I did patches to support commands like write same and compare and write > in this patchset where I made a lio rbd backend driver: > > http://www.spinics.net/lists/target-devel/msg10330.html > > but they were not accepted upstream. > > I am currently reworking the patches to be acceptable. Some distros did > pick them up though so you might see them in there. > > >> Is this possible to add this feature, as example for LIO with SCSI XCOPY? > > > The linux kernel does yet not have xcopy support like how it supports > write same or discard. There are patches, but it has not been merged > upstream. > > However, LIO does support this command by what I guess you could call > emulating it where if the underlying device does not support the command > natively then LIO will perform the operations needed. It does this for > other commands like write same too. So, even though rbd does not > currently support these commands, you can use LIO and rbd and it will > still execute them although it would not be offloaded like how you would > want. For example, for write same LIO will just do multiple writes to > the rbd device. > -- Have a nice day, Timofey. -- 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
