On Apr 4, 2010, at 8:11 PM, Edward Ned Harvey wrote: >>> There is some question about performance. Is there any additional >> overhead caused by using a slice instead of the whole physical device? >> >> No. >> >> If the disk is only used for ZFS, then it is ok to enable volatile disk >> write caching >> if the disk also supports write cache flush requests. >> >> If the disk is shared with UFS, then it is not ok to enable volatile >> disk write caching. > > Thank you. If you don't know the answer to this off the top of your head, > I'll go attempt the internet, but thought you might just know the answer in > 2 seconds ... > > Assuming the disk's write cache is disabled because of the slice (as > documented in the Best Practices Guide) how do you enable it? I would only > be using ZFS on the drive. The existence of a slice is purely to avoid > future mirror problems and the like.
This is a trick question -- some drives ignore efforts to disable the write cache :-P Use "format -e" for access to the expert mode where you can enable the write cache. As for performance benefits, YMMV. -- richard ZFS storage and performance consulting at http://www.RichardElling.com ZFS training on deduplication, NexentaStor, and NAS performance Las Vegas, April 29-30, 2010 http://nexenta-vegas.eventbrite.com _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
