On 10/20/2014 03:25 PM, 池信泽 wrote: > hi, cephers: > > When I look into the ceph source code, I found the erasure code pool > not support > the random write, it only support the append write. Why? Is that random > write of is erasure code high cost and the performance of the deep scrub is > very poor? >
To modify a EC object you need to read all chunks in order to compute the parity again. So that would involve a lot of reads for what might be just a very small write. That's also why EC can't be used for RBD images. > Thanks. > > > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > -- Wido den Hollander Ceph consultant and trainer 42on B.V. Phone: +31 (0)20 700 9902 Skype: contact42on _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
