On Thu, 15 Oct 2009, Richard Elling wrote:
No. UFS directio does 3 things: 1. unbuffered I/O 2. allow concurrent writers (no single-writer lock) 3. provide an improved async I/O code pathFor #1, the ZFS equivalent is primarycache=none, but you might find that primarycache=metadata is more appropriate, depending on your workload.
I don't think that #1 gets you all the way there for unbuffered I/O. It would have to bypass most of the I/O scheduling logic for that to work, and bypassing the I/O scheduling logic would likely invalidate zfs's ordering assurances, screw up the data layout, and lead to poor write performance.
The primarycache=none option seems to simply disable the data cache, which means that written data also does not remain in the ARC. That does not mean that written data is not buffered before it is written.
Bob -- Bob Friesenhahn bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
