Re: How to check whethera disk supports 32-bit IO

On Tue, May 18, 2010 at 7:13 PM, Glynn Clements
<[email protected]> wrote:

Thanks for the clarification .  Need some further clarification...
>
> query wrote:
>
>>     I want to know enable 32-bit IO-support on my SATA hard drive
>> using hdparm . But before I enable 32-bit support , I want to know
>> whether my hard drive supports 32-bit IO or not.
>
> The term "32-bit I/O" relates to communication between the CPU and a
> PCI IDE controller.

"The hdpam man page say "32-bit" refers to data transfers across a PCI
or VLB bus to the interface  card  only ". So , here does the
interface card is referring to the CPU.

> The concept isn't meaningful for an on-board controller.

By On-board controller do you mean to say hardware RAID device or SCSI
devices and we don't have  to set IO parameter
in such devices.



>
> As for communication between the controller and the drive, a parallel
> ATA interface is 16-bit, while SATA is serial.
>
>>          *    48-bit Address feature set
>> (is it telling that the disk supports 48-bit IO)
>
> No, it's stating that the drive supports 48-bit LBA addresses. The
> original IDE standard used 28-bit addresses which limit the size of
> the drive to 137GB (2^28 512-byte sectors).

With 48-bit addressing the limit is 144 petabytes . So , does that
mean we can install hard drive of  capacity  144 petabytes
if disks of such size are available and the BIOS supports it. Can BIOS
put a restriction on the maximum capacity of hard drive we
can install .


Thanks again .
Bz

>
> --
> Glynn Clements <[email protected]>
>
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