Date: Mon, 6 Dec 2010 22:22:35 +0100 From: Ivan Voras <ivoras@freebsd.org> To: Bruce Cran <bruce@cran.org.uk> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Pawel Jakub Dawidek <pjd@freebsd.org>, John Baldwin <jhb@freebsd.org> Subject: Re: svn commit: r216230 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs Message-ID: <AANLkTinPLsTa=S6pvxG55rK%2B3MBVRmKbha5bSZSN6w6G@mail.gmail.com> In-Reply-To: <20101206211607.GA65110@muon.cran.org.uk> References: <201012061218.oB6CI3oW032770@svn.freebsd.org> <AANLkTine9rGq_cM4ruFXYq=-F7cMXcQAr-zKHuWoQs2z@mail.gmail.com> <20101206195327.GD1936@garage.freebsd.pl> <201012061518.49835.jhb@freebsd.org> <AANLkTi=Bnkq8sR3j7kq-aKzbk0TEd=kFiyr%2BqeQpzXGc@mail.gmail.com> <20101206211607.GA65110@muon.cran.org.uk>
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On 6 December 2010 22:16, Bruce Cran <bruce@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 =C2=A0Sector size: =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0 =C2=A0 =C2=A0 512 bytes >> Physical Sector size: =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A04096 bytes >> device size with M =3D 1024*1024: =C2=A0 =C2=A0 1430799 MBytes >> device size with M =3D 1000*1000: =C2=A0 =C2=A0 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 "stripesize". 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 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0WDC WD10EARS-00Z5B1 > ... > sector size =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 logical 512, physic= al 512, offset 0 Agreed. Some drives lie.
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