> Another thing to keep an eye out for is disk caching. With ZFS, > whenever the NFS server tells us to make sure something is on disk, we > actually make sure it's on disk by asking the drive to flush dirty data > in its write cache out to the media. Needless to say, this takes a > while. > > With UFS, it isn't aware of the extra level of caching, and happily > pretends it's in a world where once the drive ACKs a write, it's on > stable storage. > > If you use format(1M) and take a look at whether or not the drive's > write cache is enabled, that should shed some light on this. If it's > on, try turning it off and re-run your NFS tests on ZFS vs. UFS. > > Either way, let us know what you find out.
Slightly OT but you just reminded me of why I like disks that have Sun firmware on them. They never have write cache on. At least I have never seen it. Read cache yes but write cache never. At least in the Seagates and Fujitsus Ultra320 SCSI/FCAL disks that have a Sun logo on them. I have no idea what else that Sun firmware does on a SCSI disk but I'd love to know :-) Dennis _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
