On Fri, Sep 12, 2014 at 1:53 AM, Kenneth Waegeman <Kenneth.Waegeman at ugent.be <javascript:;>> wrote: > > ----- Message from Sage Weil <sweil at redhat.com <javascript:;>> --------- > Date: Thu, 11 Sep 2014 14:10:46 -0700 (PDT) > From: Sage Weil <sweil at redhat.com <javascript:;>> > Subject: Re: Cephfs upon Tiering > To: Gregory Farnum <greg at inktank.com <javascript:;>> > Cc: Kenneth Waegeman <Kenneth.Waegeman at ugent.be <javascript:;>>, ceph-users > <ceph-users at lists.ceph.com <javascript:;>> > > > >> On Thu, 11 Sep 2014, Gregory Farnum wrote: >>> >>> On Thu, Sep 11, 2014 at 11:39 AM, Sage Weil <sweil at redhat.com <javascript:;>> wrote: >>> > On Thu, 11 Sep 2014, Gregory Farnum wrote: >>> >> On Thu, Sep 11, 2014 at 4:13 AM, Kenneth Waegeman >>> >> <Kenneth.Waegeman at ugent.be <javascript:;>> wrote: >>> >> > Hi all, >>> >> > >>> >> > I am testing the tiering functionality with cephfs. I used a >>> >> > replicated >>> >> > cache with an EC data pool, and a replicated metadata pool like >>> >> > this: >>> >> > >>> >> > >>> >> > ceph osd pool create cache 1024 1024 >>> >> > ceph osd pool set cache size 2 >>> >> > ceph osd pool set cache min_size 1 >>> >> > ceph osd erasure-code-profile set profile11 k=8 m=3 >>> >> > ruleset-failure-domain=osd >>> >> > ceph osd pool create ecdata 128 128 erasure profile11 >>> >> > ceph osd tier add ecdata cache >>> >> > ceph osd tier cache-mode cache writeback >>> >> > ceph osd tier set-overlay ecdata cache >>> >> > ceph osd pool set cache hit_set_type bloom >>> >> > ceph osd pool set cache hit_set_count 1 >>> >> > ceph osd pool set cache hit_set_period 3600 >>> >> > ceph osd pool set cache target_max_bytes $((280*1024*1024*1024)) >>> >> > ceph osd pool create metadata 128 128 >>> >> > ceph osd pool set metadata crush_ruleset 1 # SSD root in crushmap >>> >> > ceph fs new ceph_fs metadata cache <-- wrong ? >>> >> > >>> >> > I started testing with this, and this worked, I could write to it >>> >> > with >>> >> > cephfs and the cache was flushing to the ecdata pool as expected. >>> >> > But now I notice I made the fs right upon the cache, instead of the >>> >> > underlying data pool. I suppose I should have done this: >>> >> > >>> >> > ceph fs new ceph_fs metadata ecdata >>> >> > >>> >> > So my question is: Was this wrong and not doing the things I thought >>> >> > it did, >>> >> > or was this somehow handled by ceph and didn't it matter I specified >>> >> > the >>> >> > cache instead of the data pool? >>> >> >>> >> Well, it's sort of doing what you want it to. You've told the >>> >> filesystem to use the "cache" pool as the location for all of its >>> >> data. But RADOS is pushing everything in the "cache" pool down to the >>> >> "ecdata" pool. >>> >> So it'll work for now as you want. But if in future you wanted to stop >>> >> using the caching pool, or switch it out for a different pool >>> >> entirely, that wouldn't work (whereas it would if the fs was using >>> >> "ecdata"). > > > After this I tried with the 'ecdata' pool, which is not working because > itself is an EC pool. > So I guess specifying the cache pool is then indeed the only way, but that's > ok then if that works. > It is just a bit confusing to specify the cache pool rather than the data:) *blinks* Uh, yeah. I forgot about that check, which was added because somebody tried to use CephFS on an EC pool without a cache on top. We've obviously got some UI work to do. Thanks for the reminder! -Greg -- Software Engineer #42 @ http://inktank.com | http://ceph.com -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.ceph.com/pipermail/ceph-users-ceph.com/attachments/20140912/95587975/attachment.htm>
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