On 10/5/07, Robert Milkowski <[EMAIL PROTECTED]> wrote: > RH> 2) Also, direct I/O is faster because it avoids double buffering. > > I doubt its buying you much...
We don't know how much the performance gain is until we get a prototype and benchmark it - the behavior is different with different DBMSs, OSes, workloads (ie. I/O rate, hit ratio) etc. > However on UFS if you go with direct IO, you allow concurent writes to > the same file and you disable read-aheads - I guess it's buying you > much more in most cases than eliminating double buffering. I really hope that someone can sit down and look at the database interface provided in all the filesystems. So far, there are Direct I/O, Concurrent I/O (AIX JFS2), and Quick I/O (VxFS) http://eval.veritas.com/webfiles/docs/qiowp.pdf Then a prototype for ZFS will help us understand how much we can get... Rayson > > Now the question is - if application is usingi directio() call - what > happens if underlying fs is zfs? _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
