Date: Sun, 01 Jun 2014 12:05:51 -0400 From: Allan Jude <allanjude@freebsd.org> To: freebsd-hackers@freebsd.org Subject: Re: fdisk(8) vs gpart(8), and gnop Message-ID: <538B4F5F.2010700@freebsd.org> In-Reply-To: <538B4CEF.2030801@freebsd.org> References: <20140601004242.GA97224@bewilderbeast.blackhelicopters.org> <CAOjFWZ5N9FGwgSz0_YFNQjavzdJDitRn52VKn4ipW1ddj6-weQ@mail.gmail.com> <BCA9F5D6-3925-4E7E-9082-128652508305@FreeBSD.org> <3D6974D83AE9495E890D9F3CA654FA94@multiplay.co.uk> <538B4CEF.2030801@freebsd.org>
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On 2014-06-01 11:55, Nathan Whitehorn wrote: > On 06/01/14 08:52, Steven Hartland wrote: >> ----- Original Message ----- From: "Mark Felder" <feld@freebsd.org> >> >>> On May 31, 2014, at 20:57, Freddie Cash <fjwcash@gmail.com> wrote: >>> >>>> There's a sysctl where you can set the minimum ashift for zfs. Then you >>>> never need to use gnop. >>>> >>>> I believe it's part of 10.0? >>> >>> I've not seen this yet. What we need is to port the ability to set >>> ashift at pool creation time: >>> >>> $ zpool create -o ashift=12 tank mirror disk1 disk2 mirror disk3 disk4 >>> >>> I believe the Linux zfs port has this functionality now, but we still >>> do not. >> >> We don't have that direct option yet but you can achieve the >> same thing by setting: vfs.zfs.min_auto_ashift=12 >> > Does anyone have any objections to me changing this default, right now, > today? > -Nathan > > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" The only other downside to 4k sectors is that you only get a history of 32 transaction groups instead of 128. Matt Ahrens says this isn't a big deal. I agree with changing the default to 12, a user making a new pool with 512b disks that is that worried about performance, can always shift the value back to 9. I will add this to the zfs section of the handbook, and make a specific note about this 512b issue. The 18,000 word ZFS section of the handbook should go live within a week or two. -- Allan Jude
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