On Monday March 17, akpm@digeo.com wrote: > Neil Brown <neilb@cse.unsw.edu.au> wrote: > > > > These two symptoms strongly suggest a buffer aliasing problem. > > i.e. you have two buffers (one for data and one for metadata) > > that refer to the same location on disc. > > One is part of a file that was recently deleted, but the buffer hasn't > > been flushed yet. The other is part of a new directory. > > The old buffer and the new buffer both get written to disc at much the > > same time (hence the "multiple 1 requests"), but the old buffer hits > > the disc second and so corrupts the filesystem. > > This aliasing can happen very easily with direct-io, and it is something > which drivers should be able to cope with. > > I hope RAID is not still assuming that all requests are unique in this way? No. RAID copes. If raid5 sees a write request for a block that it already has a pending write request for, it will print a warning and delay the second until the first complete. In the cas in question I don't think raid5 is contributing to the problem. It is just provide extra information which might help point towards the problem - i.e. it is confirming that some sort of aliasing is happening. NeilBrown _______________________________________________ Ext3-users@redhat.com https://listman.redhat.com/mailman/listinfo/ext3-users
