Status of support for 4KB disk sectors

Ivan Voras ivoras at
Tue Jul 19 19:30:19 UTC 2011

On 19.7.2011. 19:54, Chuck Swiger wrote:
> On Jul 18, 2011, at 11:04 PM, Kevin Oberman wrote:
>> I just wish FreeBSD had some decent documentation on such a fundamental
>> operation. Fortunately there are some pretty good articles folks have
>> written, but they did leave me with several questions.
> Is there something in FreeBSD which is preventing you from using the drive's native DEV_BSIZE of 4096 bytes, or is it that the drive claims to have a physical block size of 512 bytes when it is really 4k?

Nope, "only" that.

The current state of the matter (i.e. for 9.0) is:

  * The new ATA driver has quirks for certain models of HDDs which have 
this false advertising (which can be manually triggered by which causes the drive to report stripesize of 4k.

  * This information is used in gpart to size & align partitions; it 
will be used by the new installer

  * Default fragment size for UFS was raised to 4K so it will be aligned 
by default.

More information about the freebsd-stable mailing list