Strange Intel Mobo Behavior
tundra at tundraware.com
Mon Jun 4 06:23:22 UTC 2007
r17fbsd at xxiii.com wrote:
> At 02:08 PM 6/3/2007, Tim Daneliuk wrote:
>> 3) Both the MOBO and drive are SATA-300 rated, but 6.2 insists that
>> the drive is running at SATA-150. I have verified that the drive
>> has no jumper forcing it into this mode.
> Don't know about the other issues, but I have a Dell with similar Intel
> components, and it did the same SATA thing when I put a new drive in it
> atapci1: <Intel ICH7 SATA300 controller> port
> irq 20 at device 31.2 on pci0
> ad4: 76293MB <Maxtor 6L080M0 BACE1G10> at ata2-master SATA150
> ad6: 305245MB <Seagate ST3320620AS 3.AAK> at ata3-master SATA150
> The ad6 drive is supposed to do SATA-300, but realistically, other
> bottlenecks dictate it's not going to get anywhere near the '150 speed,
Could you comment a bit more on why you think this is so. I would
think that with modern processors and buses, a machine with light load
ought to be able to drive SATA-300, but I've never actuall tested for
> so I'm not terribly worried about it. cp'ing a 4GB file to /dev/null
> yielded 57MB/sec.
I get around 50MB/sec or so with about 2G file, so we're in the same
ballpark. In round numbers, this is 1/3 the theoretical throughput
of a SATA-150 or 1/6 that of SATA-300. Now, I *am* curious on what
the bottlenecks are. 50MB/sec isn't a whole lot different that what
I'd expect out of a modern PATA drive. So, noting the better cabling
and the wide availability of on-board RAID, it sure looks to me like there
is no compelling argument to be made for SATA in non-RAIDed environments.
I'm guessing the drives are the same ones as their PATA counterparts, just
with different interface electronics, so we're not going to see SCSI-like
reliability and/or performance under load.
I can understand some overhead due to system dispatching and multitasking,
but in a lightly loaded machine (as mine was when I did the test) with
2G of memory and dual 3.2G processors, it seems very strange that the
drive should run at 1/3 or less the stated interface speed. What am I
missing here, I wonder...
Tim Daneliuk tundra at tundraware.com
PGP Key: http://www.tundraware.com/PGP/
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