Thanks Jason, yes, I also do not think they can guarantee atomic in extent level. But for a stripe unit in a object, can the atomic write be guaranteed? thanks.
2016-04-06 19:53 GMT+08:00 Jason Dillaman <[email protected]>: > It's possible for a write to span one or more blocks -- it just depends on > the write address/size and the RBD image layout (object size, "fancy" > striping, etc). Regardless, however, RBD cannot provide any ordering > guarantees when two clients are writing to the same image at the same > extent. To safely use two or more clients concurrently on the same image > you need a clustering filesystem on top of RBD (e.g. GFS2) or the > application needs to provide its own coordination to avoid concurrent > writes to the same image extents. > > -- > > Jason Dillaman > > > ----- Original Message ----- > > > From: "min fang" <[email protected]> > > To: "ceph-users" <[email protected]> > > Sent: Tuesday, April 5, 2016 10:11:10 PM > > Subject: [ceph-users] ceph rbd object write is atomic? > > > Hi, as my understanding, ceph rbd image will be divided into multiple > objects > > based on LBA address. > > > My question here is: > > > if two clients write to the same LBA address, such as client A write > "aaaa" > > to LBA 0x123456, client B write "bbbb" to the same LBA. > > > LBA address and data will only be in an object, not cross two objects. > > > Will ceph guarantee object data must be "aaaa" or "bbbb"? "aabb", "bbaa" > will > > not happen even in a stripe data layout model? > > > thanks. > > > _______________________________________________ > > ceph-users mailing list > > [email protected] > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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