proper newfs options for SSD disk

[Tim Kientzle]

On May 22, 2012, at 7:40 AM, Warren Block wrote:

> On Tue, 22 May 2012, Matthias Apitz wrote:
> 
>> El día Tuesday, May 22, 2012 a las 07:42:18AM -0600, Warren Block escribió:
>> 
>>> On Tue, 22 May 2012, Matthias Apitz wrote:
>>> 
>>>> El día Sunday, May 20, 2012 a las 03:36:01AM +0900, rozhuk.im at gmail.com escribió:
>>>>> 
>>>>> Do not use MBR (or manually do all to align).
>>>>> 63 - not 4k aligned.
>>>> 
>>>> To create the above shown partition layout I have not used gpart(8); I
>>>> just said:
>>>> 
>>>>   # fdisk -I /dev/ada0
>>>>   # fdisk -B /dev/ada0
>>>> 
>>>> ...
>>>> What is wrong with this procedure?
>>> 
>>> The filesystem partitions end up at locations that aren't even multiples
>>> of 4K.  This can reduce performance.  How much probably depends on the
>>> SSD.
>> 
>> But this is then rather a bug in fdisk(8) and not a PEBKAC, or? :-)
> 
> A bug in the design of MBR.  Which probably can be forgiven, considering when it was created and the other problems with it. :)
> 
> gpart's alignment option can be used with MBR slices and bsdlabel partitions.

GPart's alignment option doesn't work for MBR slices.
It rounds to the requested alignment, and then rounds again
to the track size, which defaults to 63 sectors.

I'm not convinced this is a bug in the design of MBR.  I don't
think anything in the MBR design requires that partitions
be track-aligned.

Tim