svn commit: r216230 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs

Ivan Voras ivoras at
Mon Dec 6 21:23:17 UTC 2010

On 6 December 2010 22:16, Bruce Cran <bruce at> wrote:
> On Mon, Dec 06, 2010 at 09:31:39PM +0100, Ivan Voras wrote:
>> For what it's worth, apparently linux has the concept of "physical"
>> and "logical" sector sizes (possibly in addition to "stripe size"),
>> with physical being 4096 and logical 512, for example:
>> # hdparm -I /dev/sde | grep size
>> Logical  Sector size:                   512 bytes
>> Physical Sector size:                  4096 bytes
>> device size with M = 1024*1024:     1430799 MBytes
>> device size with M = 1000*1000:     1500301 MBytes (1500 GB)
> So do we, except they're both the same for Advanced Format drives:

There is a subtle difference here which may be important. We have the
concepts of "sectorsize" and "stripesize".

I think camcontrol actually reports logical and physical sector sizes
as reported by low-level drivers but currently GEOM names "logical
sector size" as "sectorsize" and "physical sector size" as

The term "stripesize" can be overloaded to mean both the item in
question - 4 KiB physical sector sizes and RAID stripe sizes. I think
this situation is bad and that the two meanings should be split.

> # camcontrol identify /dev/ada1
> ...
> device model            WDC WD10EARS-00Z5B1
> ...
> sector size             logical 512, physical 512, offset 0

Agreed. Some drives lie.

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