Hi Wido: Thanks for your kindness, i checked the codes just now, seems there were no overload related thing in CRUSH codes. It is a little bit not consistent with the CRUSH paper. So if the %100 utilized OSD is returned, the objects will still be written on the underlined storage device? How about the device failure case? All the objects on the failure device will be replicated to the good ones? once the device is recoverd, the data will be replicated back? Best Regards Zou On Fri, Jun 6, 2014 at 4:27 PM, Wido den Hollander <wido@xxxxxxxx> wrote: > On 06/06/2014 10:14 AM, zou wonder wrote: >> >> Hi buddies, >> >> I am doing investigation on Ceph and Swift,and I am newbie to Ceph. >> >> I am unclear to the behaviour of the Ceph when there is overload >> situation. >> According to the doc, when Ceph do CRUSH, if it find the OSD is overload, >> it will skip it to select the other OSD. It means if the OSD don't get >> overloaded >> the object should be put in this OSD. So how about the original on put on >> this OSD when it is not get overloaded? >> Can we read it ? When doing CRUSH , the OSD will be skip. >> > > CRUSH will not take any performance characteristics into account. If a OSD > is 100% utilized it will still be selected by CRUSH. > > Keep in mind however that Block Devices are striped in 4MB chunks and the > same happens for Objects stored via the RADOS Gateway. > >> If my understanding is wrong, please correct me. >> >> Best Regards, >> zou >> -- >> 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 >> > > > -- > Wido den Hollander > 42on B.V. > Ceph trainer and consultant > > Phone: +31 (0)20 700 9902 > Skype: contact42on -- 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
