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Date:      Mon, 2 Jun 2014 18:03:26 +0100
From:      "Steven Hartland" <killing@multiplay.co.uk>
To:        "Allan Jude" <allanjude@freebsd.org>, <freebsd-hackers@freebsd.org>
Subject:   Re: fdisk(8) vs gpart(8), and gnop
Message-ID:  <EC2C2153C64340E8ACA9DD20EF9D79C5@multiplay.co.uk>
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> <1DB2D63312CE439A96B23EAADFA9436E@multiplay.co.uk> <538B4FD7.4090000@freebsd.org> <538C7035.5080700@freebsd.org>

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----- Original Message ----- 
From: "Allan Jude" <allanjude@freebsd.org>


> On 2014-06-01 12:07, Nathan Whitehorn wrote:
>> 
>> So the discussion here is related to what to do about the installer. The
>> current ZFS component unconditionally creates gnops all over the place
>> to set ashift to 4k. That's across the board worse: it has exactly the
>> performance impact of changing the default of this sysctl (whatever that
>> is), it can't easily be overridden (which the sysctl can), and it's a
>> horrible hack to boot. There are a few options:
>> 
>> 1. Change the default of vfs.zfs.min_auto_ashift
>> 2. Have the same effect but in a vastly worse way by adjusting the
>> installer to create gnops
>> 3. Have ZFS choose by itself and decide to do that permanently.
>> 
>> Our ATA code is good about reporting block sizes now, so (3) isn't a big
>> issue except for the mixed-pool case, which is a huge PITA.
>> 
>> We need to choose one of these. I favor (1).
>> -Nathan
>
> I favour 1 as well.
> 
> Note: the current ZFS installer script forces 4k with gnop if the option
> is turned on (it is by default), but you can have it not use gnop.
> 
> But yes, this new sysctl (it is very new), is great. Will it be MFC'd in
> time for 9.3?

I MFC'ed to stable/10 and stable/9 ~2 weeks so yes :)



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