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Date: Thu, 21 Oct 2010 08:43:41 -0700
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From: Freddie Cash <fjwcash@gmail.com>
To: Adam Nowacki <nowak@xpam.de>
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Cc: freebsd-fs@freebsd.org
Subject: Re: ZFS and Samsung Spinpoint F4 4K sector drive
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On Thu, Oct 7, 2010 at 6:53 PM, Adam Nowacki <nowak@xpam.de> wrote:
> Nothing user friendly but if you're willing to modify sources and rebuild
> kernel there is a one line tweak.
>
> /usr/src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c find:
> *ashift = highbit(MAX(pp->sectorsize, SPA_MINBLOCKSIZE)) - 1;
> and modify to something like:
> *ashift = highbit(MAX(MAX(4096, pp->sectorsize), SPA_MINBLOCKSIZE)) - 1;
>
> I'm using this for 3 months with 20 2TB 4kb sector WDC disks (in 2 raidz2
> arrays of 10) without any issues. Writes go at 300MB/s.

Does this patch work the same was as the following:
http://www.solarismen.de/archives/5-Solaris-and-the-new-4K-Sector-Disks-e.g.-WDxxEARS-Part-2.html

They both deal with setting ashift to 4096 bytes, but are in two very
different places in the code.

-- 
Freddie Cash
fjwcash@gmail.com