We are on Giant. On 03/16/2015 02:03 PM, Azad Aliyar wrote: > > May I know your ceph version.?. The latest version of firefly 80.9 has > patches to avoid excessive data migrations during rewighting osds. You > may need set a tunable inorder make this patch active. > > This is a bugfix release for firefly. It fixes a performance regression > in librbd, an important CRUSH misbehavior (see below), and several RGW > bugs. We have also backported support for flock/fcntl locks to ceph-fuse > and libcephfs. > > We recommend that all Firefly users upgrade. > > For more detailed information, see > http://docs.ceph.com/docs/master/_downloads/v0.80.9.txt > > Adjusting CRUSH maps > -------------------- > > * This point release fixes several issues with CRUSH that trigger > excessive data migration when adjusting OSD weights. These are most > obvious when a very small weight change (e.g., a change from 0 to > .01) triggers a large amount of movement, but the same set of bugs > can also lead to excessive (though less noticeable) movement in > other cases. > > However, because the bug may already have affected your cluster, > fixing it may trigger movement *back* to the more correct location. > For this reason, you must manually opt-in to the fixed behavior. > > In order to set the new tunable to correct the behavior:: > > ceph osd crush set-tunable straw_calc_version 1 > > Note that this change will have no immediate effect. However, from > this point forward, any 'straw' bucket in your CRUSH map that is > adjusted will get non-buggy internal weights, and that transition > may trigger some rebalancing. > > You can estimate how much rebalancing will eventually be necessary > on your cluster with:: > > ceph osd getcrushmap -o /tmp/cm > crushtool -i /tmp/cm --num-rep 3 --test --show-mappings > /tmp/a 2>&1 > crushtool -i /tmp/cm --set-straw-calc-version 1 -o /tmp/cm2 > crushtool -i /tmp/cm2 --reweight -o /tmp/cm2 > crushtool -i /tmp/cm2 --num-rep 3 --test --show-mappings > /tmp/b > 2>&1 > wc -l /tmp/a # num total mappings > diff -u /tmp/a /tmp/b | grep -c ^+ # num changed mappings > > Divide the total number of lines in /tmp/a with the number of lines > changed. We've found that most clusters are under 10%. > > You can force all of this rebalancing to happen at once with:: > > ceph osd crush reweight-all > > Otherwise, it will happen at some unknown point in the future when > CRUSH weights are next adjusted. > > Notable Changes > --------------- > > * ceph-fuse: flock, fcntl lock support (Yan, Zheng, Greg Farnum) > * crush: fix straw bucket weight calculation, add straw_calc_version > tunable (#10095 Sage Weil) > * crush: fix tree bucket (Rongzu Zhu) > * crush: fix underflow of tree weights (Loic Dachary, Sage Weil) > * crushtool: add --reweight (Sage Weil) > * librbd: complete pending operations before losing image (#10299 Jason > Dillaman) > * librbd: fix read caching performance regression (#9854 Jason Dillaman) > * librbd: gracefully handle deleted/renamed pools (#10270 Jason Dillaman) > * mon: fix dump of chooseleaf_vary_r tunable (Sage Weil) > * osd: fix PG ref leak in snaptrimmer on peering (#10421 Kefu Chai) > * osd: handle no-op write with snapshot (#10262 Sage Weil) > * radosgw-admi > > > > > On 03/16/2015 12:37 PM, Alexandre DERUMIER wrote: > >>> VMs are running on the same nodes than OSD > > Are you sure that you didn't some kind of out of memory. > > pg rebalance can be memory hungry. (depend how many osd you have). > > 2 OSD per host, and 5 hosts in this cluster. > hosts h > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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