Re: Disks w/non-512-byte sectors?

[mlelstv%serpens.de@localhost (Michael van Elst)]

jdbaker%mylinuxisp.com@localhost ("John D. Baker") writes:

>I was of the impression that the 4K sector business was to address(!)
>the problem of disk capacity outrunning the addressing capacity of the
>Task File interface on IDE/PATA/SATA disks, evening with all the funky
>bit reassignments to squeeze out more address space and LBA tricks.

Current disks have LBA48, 48bit to address a sector. That's 128 Petabytes
(131072 Terabytes) with 512-byte sectors.


>The above sounds like it's just a performance issue at the DAC level.

The larger sectors reduce per-sector command overhead and also squeeze
a few bits more onto the disk.


>I wonder if some I already have are 4K underneath.  That might account
>for the rather poor performance I get.  Is there any way to tell?  I
>forget where IBM/Hitachi disks ended up so I know where to look.

SATA is supposed to tell you, but I wouldn't trust the information
returned by the 512byte-emulated disks. Best is just to look up
the specs for a specific drive model.

N.B. drives in USB enclosures often do not use the emulated sector
sizes.

-- 
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."