Re: btrfs on whole disk (no partitions)

[George Mitchell <george@chinilu.com>]

On 06/22/2014 07:11 AM, Roman Mamedov wrote:
> On Sun, 22 Jun 2014 06:44:13 -0700
> George Mitchell <george@chinilu.com> wrote:
>
>> On 06/22/2014 12:49 AM, Imran Geriskovan wrote:
>>>> The 64KB Btrfs bootloader pad is 8 sector aligned, so for 512e AF disks
>>>> there's no problem formatting the whole drive. The alignment problem
>>>> actually happens when partitioning it, using old partition tools that don't
>>>> align on 8 sector boundaries. There are some such tools still floating
>>>> around.
>>> A 'somewhat' related question:
>>>
>>> So called Advanced Format drives has 4K physical sector size,
>>> however they report 512B logical sector size.
>>>
>>> How does linux kernel access those drives?
>>> 512B or 4K at a time?
>> This is a problem related to Western Digital drives.  They lie in order
>> to be compatible with older versions of Windows.
> Wake up and smell the coffee.
>
> Device Model:     HGST HTE725050A7E630
> Sector Sizes:     512 bytes logical, 4096 bytes physical
>
>
> Device Model:     TOSHIBA DT01ACA050
> Sector Sizes:     512 bytes logical, 4096 bytes physical
>
>
> The "AF" standard as accepted by the industry does include this "lying", and
> it's not just WD doing this by any stretch of the imagination. Aside from
> USB-only drives (which lack the ability to be plugged into SATA), no one can
> afford to produce and  a drive incompatible with Windows these days. In fact
> I'd be glad if you could support your Seagate 4K claim by any model names and
> their smartctl output.
>
I am not sure I see anything wrong with that.  They are showing a 
physical block size of 4096.  And it is the physical block size we care 
about.  As I recall Western Digital drives, at least in the beginning, 
were reporting 512 physical.  That was the problem.