There's some prefetching and stuff, but the rbd library and RADOS storage are capable of issuing reads and writes in any size (well, down to the minimal size of the underlying physical disk). There are some scenarios where you will see it writing a lot more if you use layering -- promotion of data happens a full object at a time. -Greg
On Thursday, June 5, 2014, Cédric Lemarchand <c.lemarch...@yipikai.org> wrote: > I would think that rbd block are like stripes for RAID or blocks for hard > drives, even if you only need to read or write 1k, the full stripe has to > be read or write. > > Cheers > > -- > Cédric Lemarchand > > > Le 5 juin 2014 à 22:56, Timofey Koolin <timo...@koolin.ru <javascript:;>> > a écrit : > > > > Do for every read/write rbd read/write full block of data (4MB) or rbd > can read/wite part of block? > > > > For example - I have a 500MB file (database) and need random read/write > by blocks about 1-10Kb. > > > > Do for every read 1 Kb rbd will read 4MB from hdd? > > for write? > > > > > > _______________________________________________ > > ceph-users mailing list > > ceph-users@lists.ceph.com <javascript:;> > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com <javascript:;> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > -- Software Engineer #42 @ http://inktank.com | http://ceph.com
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