On 10/08/13 22:25, Freddie Cash wrote: > On Tue, Oct 8, 2013 at 1:17 PM, Nathan Whitehorn > <nwhiteh...@freebsd.org <mailto:nwhiteh...@freebsd.org>>wrote: > > 4. What is this gnop stuff for? > > > Can't comment on the rest, but gnop is required to create 4K-aligned > vdevs where the minimum block size is 4K (aka ashift=12). Without > this, ZFS relies on the underlying disk driver providing the correct > information, and most don't. Also, if you don't do this, and create a > vdev using 512B sectors, the ashift will be set to 9, and replacing > the drive down the line with 4K Advanced Format drive will drop your > drive performance in the toilet. > > Thus, to future-proof your pool, you need to: > - set the ashift of the pool to 12 (4 KB) > - align the disk/partition on 4 KB boundaries (starting partition at > 1 MB works well) > > Until our ZFS gains the ability to set a minimum ashift for the pool, > or to set the ashift at vdev creation, or all drive manufacturers > write perfect firmware, than we need to fake it with gnop. >
Well, that's a disgusting hack, but I see why it's there. Thanks for the explanation! -Nathan _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
