Hi, to avoid confusion I would name the "host" entries in the crush map differently. Make sure these host names can be resolved to the correct boxes though (/etc/hosts on all the nodes). You're also missing a new rule entry (also shown in the link you mentioned). Lastly, and this is *extremely* important: You need to set [global] osd crush update on start = false in your ceph.conf because there is currently no logic for OSDs to detect their location with different roots present as "documented" here: http://tracker.ceph.com/issues/6227 If you don't set this, whenever you start an OSD belonging to your SSD root, it will move the OSD over to the default root. Side note: this is really unfortunate since with cache pools it is now common to have platters and SSDs on the same physical hosts and also multiple parallel roots. On 10/07/2014 17:04, Nikola Pajtic wrote: > Hello to all, > > I was wondering is it possible to place different pools on different > OSDs, but using only two physical servers? > > I was thinking about this: http://tinypic.com/r/30tgt8l/8 > > I would like to use osd.0 and osd.1 for Cinder/RBD pool, and osd.2 and > osd.3 for Nova instances. I was following the howto from ceph > documentation: > http://ceph.com/docs/master/rados/operations/crush-map/#placing-different-pools-on-different-osds > , but it assumed that there are 4 physical servers: 2 for "Platter" pool > and 2 for "SSD" pool. > > What I was concerned about is how the CRUSH map should be written and > how the CRUSH will decide where it will send the data? Because of the > the same hostnames in cinder and nova pools. For example, is it possible > to do something like this: > > > # buckets > host cephosd1 { > id -2 # do not change unnecessarily > # weight 0.010 > alg straw > hash 0 # rjenkins1 > item osd.0 weight 0.000 > } > > host cephosd1 { > id -3 # do not change unnecessarily > # weight 0.010 > alg straw > hash 0 # rjenkins1 > item osd.2 weight 0.010 > } > > host cephosd2 { > id -4 # do not change unnecessarily > # weight 0.010 > alg straw > hash 0 # rjenkins1 > item osd.1 weight 0.000 > } > > host cephosd2 { > id -5 # do not change unnecessarily > # weight 0.010 > alg straw > hash 0 # rjenkins1 > item osd.3 weight 0.010 > } > > root cinder { > id -1 # do not change unnecessarily > # weight 0.000 > alg straw > hash 0 # rjenkins1 > item cephosd1 weight 0.000 > item cephosd2 weight 0.000 > } > > root nova { > id -6 # do not change unnecessarily > # weight 0.020 > alg straw > hash 0 # rjenkins1 > item cephosd1 weight 0.010 > item cephosd2 weight 0.010 > } > > If not, could you share an idea how this scenario could be achieved? > > Thanks in advance!! > >
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