On Sep 1, 2015 4:41 PM, "Janusz Borkowski" <janusz.borkow...@infobright.com> wrote: > > Hi! > > open( ... O_APPEND) works fine in a single system. If many processes write to the same file, their output will never overwrite each other. > > On NFS overwriting is possible, as appending is only emulated - each write is preceded by a seek to the current file size and race condition may occur. > > How it is in cephfs?
CephFS generally ought to handle appends correctly. If it's not we will want to fix that. > > I have a file F opened with O_APPEND|O_WRONLY by some process. In a console I type > > $ echo "asd" >> F > > Effectively, this is opening of file F by another process with O_APPEND flag . > > The string "asd" is written to the beginning of file F, overwriting the starting bytes in the file. Is it a bug or a feature? If a feature, how it is described? Are you doing this in the same box that's got the the file open, or a different one? Are you using the ceph-fuse or kernel clients on the systems? I'm not sure how the shell actually handles >> so I'd like to see this reproduced with strace or an example program to be sure it's really not handling append properly. -Greg > > It is ceph Hammer and kernel 3.10.0-229.11.1.el7.x86_64 > > Thanks! > > J. > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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