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Re: SATA vs PATA



[This message has also been posted to linux.debian.user.]
In article <8WMZ2-6vj-11@gated-at.bofh.it>, Douglas A. Tutty wrote:
> On Mon, Aug 27, 2007 at 12:05:42PM +0200, Dan H wrote:
>> Should I go Serial-ATA or good ol' Parallel-ATA? How do the two
>> compare in terms of data throughput and Linux kernel support?
>> 
>
> SATA-I gives 150 MB/s, SATA-II gives 300 MB/s, PATA 133 MB/s.

PATA/133 was a flaky kludge.  It's amazing it worked at
all.  Even more amazing that people got away with cables
over 18" long.  SATA is a far superior interconnect.

The instantaneous peak throughput of the original
(four bytes wide, 33 MHz) PCI bus is 132 MB/sec.  In real life
you're not going to see over 90.  So a SATA-II controller
on a regular PCI card is bottlenecked at the motherboard slot.
(So is 1000BASE-T Ethernet.)  That's one reason "real hardware"
RAID works better than "fakeraid."  
The smallest PCI Express (PCI-E) configuration should do 250 MB/sec
in each direction simultaneously.  A motherboard with PCI-E
designed for workstations may bottleneck at the southbridge.

You'll have to do some research to find a configuration that
can run two SATA-II drives simultaneously at their full data rate.
You'll also have to check around to see if the Linux driver knows
how to run any particular controller in SATA-II mode.
And there are still lots of workstation type motherboards that only
do SATA-I.

PCI-X is a kludge.  I'd avoid it.


Cameron




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