svn commit: r216230 -
mav at FreeBSD.org
Mon Dec 6 21:49:13 UTC 2010
On 06.12.2010 23:22, Ivan Voras wrote:
> On 6 December 2010 22:16, Bruce Cran<bruce at cran.org.uk> 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".
It is only question of abstraction. As soon as any our disk device is
GEOM abstraction - don't see reason why parameters should be specific.
> 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
`camcontrol identify` directly requests IDENTIFY data and parses them.
There is nobody between it and the device. To see what GEOM receives
from the disk driver use diskinfo.
> 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.
There could be a long list of different "stripesize" sources. It is not
a task of the partitioning tool or file system to know all of them. As I
have described in previous email - only size matters.
>> # camcontrol identify /dev/ada1
>> device model WDC WD10EARS-00Z5B1
>> sector size logical 512, physical 512, offset 0
> Agreed. Some drives lie.
"Everybody lies". :) If Linux example was taken from page I've seen - it
was external WD USB storage somehow reporting that physical sector size,
not the disk itself. I haven't seen proper reporting in any WD drive yet
(started to think about adding quirk at ada driver). Now waiting for
Seagate 4K disks reports to check how bad things are.
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