5 Nov
2010
5 Nov
'10
5:47 p.m.
On 11/5/10 8:37 PM, Nigel Williams wrote:
It's done in the low-level formatting. When you tell the drive to
format itself, you set its block size.
The blocks
themselves
are nearly always formatted to 512 bytes per block (though in the
earliest days, 256 bytes per block was not unknown), and the blocks
can be just read out sequentially starting with 0000000 (which is
something 'dd' is exceptionally good at).
Out of curiosity what determines the 512-bytes per block setting on a
common SCSI hard drive? Is this done with low-level formatting and is
that in the drives firmware or an external utility? I understand that the IBM AS/400 machines for example
use 520-byte
sectors, so does it mean that a common SCSI hard drive with 512-byte
sectors can never be used with an AS/400 or is just a matter of
low-level formatting? has anyone ever attempted this?
The latter. I have reformatted lots of weird-sector-size SCSI drives
back to 512 byte sectors. I've gotten drives formatted to 520 bytes,
576 bytes, and (I think) 640 bytes. I don't recall having formatted
*away* from 512 byte sectors, but that shouldn't be an issue.
I have an old CISC AS/400 and I am wondering what the
long term
options are going to be for spinning storage.
I think you'll be ok. The worst that'll happen is you'll need to
find a fancy SCSI utility to reformat your drive while giving you a lot
of control over *how* it's reformatted.
-Dave
--
Dave McGuire
Port Charlotte, FL