File system blocks alignment

Miroslav Lachman 000.fbsd at
Mon Dec 28 11:58:29 UTC 2009

Alexander Motin wrote:
> Thomas Backman wrote:
>> On Dec 25, 2009, at 11:58 AM, Alexander Motin wrote:
> |>>  Recently WD released first series of ATA disks with increased physical
>>> sector size. It makes writes not matching with 4K blocks inefficient
>>> there.
>> They don't expose this to the OS, though (not by default, anyway), but chop it up into 8 512-byte sectors for compatibility reasons.
>> Just thought I'd point that out - I'm not even sure if you can get them to *not* do the compatibility thing and expose 4k-sized sectors.
> Latest ATA-8 specification allows drive to report both logical (512B)
> and physical (4KB) sector sizes. ada driver able to fetch and report
> that info to GEOM. If these drives not reporting it yet (are you really
> sure?), it is only question of their firmware.

There is an article about 4k sectors

It is completely hidden to OS in first versions.

Miroslav Lachman

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