fdisk(8) vs gpart(8), and gnop

[Matthew Ahrens]

On Sun, Jun 1, 2014 at 8:55 AM, Nathan Whitehorn <nwhitehorn at freebsd.org>
wrote:

> On 06/01/14 08:52, Steven Hartland wrote:
>
>> ----- Original Message ----- From: "Mark Felder" <feld at freebsd.org>
>>
>>  On May 31, 2014, at 20:57, Freddie Cash <fjwcash at 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.
>>>
>>
I am strongly against implementing "-o ashift=12"[*].  If we need to
explicitly tell ZFS what sector size to use, we should make that intention
clear with an appropriately named property, for example "-o
device_sector_size=4K".  Even better, this property should be per-disk.

--matt

[*]  Once we implement an appropriately-named property, I would be OK with
also allowing the "-o ashift=12" as a Linux compatibility feature.



>
>> 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
>
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