[K12OSN] K12linux and SCSI... any thoughts?

Robert Arkiletian robark at gmail.com
Tue Jul 12 17:31:05 UTC 2005

On 7/11/05, Patrick Sawyer <patricksawyer at gmail.com> wrote:
> What does the community think of scsi and K12?

Right now scsi is your best choice. But by the end of this year SATA
II should be an option for us. SATA II comes with ncq which is the
same as tcq in scsi drives and also 300 MB/s max data transfer rate.
The drive/controller/OS are capable of sending/receiving multiple i/o
operations to the disk at once and let the disk determine most
efficient head movement strategy. Very important in servers. IDE or
regular SATA  drives will kill themselves doing all requests in order
(too much head movement) That's why you hear that thrashing noise.
Plus scsi drives have higher rpm and I believe they are manufactured
to a higher standard. The main advantage of SATA II is that it will be
MUCH cheaper than scsi. For example you can buy 250GB sata for ~$150
CAD but a 36GB scsi costs ~$225 CAD. I believe SATA II will have taken
a big share of the scsi market in about a year.

BTW as far as I know the only chipsets that fully support SATA II
right now are the intel ICH7 which comes paired with the Intel 945/955
northbridges and the nvidia nforce4. The Intel 915/925 and the Sil
3124 support ncq but not the entire SATA II spec. The upcoming VIA
8251 southbridg and the Silicon image 3132 pci-e card support SATA II.
I am guessing they will be available by Sept. However, kernel support
is in the works and drive manufacturers are slowly supporting ncq.
Although I have not seen any SATA II drives for sale yet. Like I said,
x-mas is when I think everything will come together for SATA II and

One other thing to note. Currently we must depend on scsi controller
manufacturers to provide driver source. Some do better than others.
But the AHCI spec is open. I know that controllers which follow the
spec will be FULLY supported by linux out of the box. Currently the
only ones I know that do are Intel, Sil and upcoming VIA. Nvidia does
NOT. That's why I won't buy Nvidia nforce4 MB. See this site for
further details.


Robert Arkiletian
C++ GUI tutorial http://fltk.org/links.php?V19

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