On Sun, 26 Jul 2009, David Magda wrote:
That's the whole point of this thread: what should happen, or what should the file system do, when the drive (real or virtual) lies about the syncing? It's just as much a problem with any other POSIX file system (which have to deal with fsync(2))--ZFS isn't that special in that regard. The Linux folks went through a protracted debate on a similar issue not too long ago:
Zfs is pretty darn special. RAIDed disk setups under Linux or *BSD work differently than zfs in a rather big way. Consider that with a normal software-based RAID setup, you use OS tools to create a virtual RAIDed device (LUN) which appears as a large device that you can then create (e.g. mkfs) a traditional filesystem on top of. Zfs works quite differently in that it is uses a pooled design which incorporates several RAID strategies directly. Instead of sending the data to a virtual device which then arranges the underlying data according to a policy (striping, mirror, RAID5), zfs incorporates knowledge of the vdev RAID strategy and intelligently issues data to the disks in an ideal order, executing the disk drive commit requests directly. Zfs removes the RAID obfustication which exists in traditional RAID systems.
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
