Hi, from my experience both "ceph osd crush reweight" and "ceph osd reweight" will lead to CRUSH map changes and PGs remapping. So both commands eventually redistribute data beween OSDs. Is there any good reason in terms of ceph performance best practices to choose the one over the other?
On 26 June 2014 20:05, Gregory Farnum <g...@inktank.com> wrote: > On Thu, Jun 26, 2014 at 7:03 AM, Micha Krause <mi...@krausam.de> wrote: >> Hi, >> >> could someone explain to me what the difference is between >> >> ceph osd reweight >> >> and >> >> ceph osd crush reweight > > "ceph osd crush reweight" sets the CRUSH weight of the OSD. This > weight is an arbitrary value (generally the size of the disk in TB or > something) and controls how much data the system tries to allocate to > the OSD. > > "ceph osd reweight" sets an override weight on the OSD. This value is > in the range 0 to 1, and forces CRUSH to re-place (1-weight) of the > data that would otherwise live on this drive. It does *not* change the > weights assigned to the buckets above the OSD, and is a corrective > measure in case the normal CRUSH distribution isn't working out quite > right. (For instance, if one of your OSDs is at 90% and the others are > at 50%, you could reduce this weight to try and compensate for it.) > > It looks like our docs aren't very clear on the difference, when it > even mentions them...and admittedly it's a pretty subtle issue! > -Greg > Software Engineer #42 @ http://inktank.com | http://ceph.com > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
