zfs on 4k sector disks

[Pawel Jakub Dawidek]

On Sat, Feb 20, 2010 at 01:25:54PM +0100, Dimitry Andric wrote:
> On 2010-02-20 10:47, mailinglists wrote:
> >This "Advanced Format" basically means the sectors size on disk is
> >changed to 4k in stead of 512k.
> 
> Please note those disks still seem to expose 512B sectors to any OS; the
> 4kiB sectors are only used internally.  And there seems to be no jumper
> to "fix" this behaviour...  Unaligned writes can cause multiple
> read-write-modify operations, which are most likely bad for performance.

You can "fix" that with:

	# gnop create -S 4096 /dev/ad0

This command will create /dev/ad0.nop provider, which will expose 4kB
sector (see diskinfo(8)). Unfortunately gnop won't survive reboot, as it
doesn't use any metadata.

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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