Grant Grundler wrote:
Linda,
Please tell us which kernel version you have and include the dmesg
output. Port multiplier support is generally working in 2.6.26 (and later
releases) for several drivers. PM support was added after 2.6.20.
---
Sorry. I'm a bit behind the edge at 2.6.27.3 --
but I tried a boot w/2.6.28.3 and didn't see a difference (had to return
to 27.3 as I accidently disabled a different driver and haven't regened it.
Where did you find 350MB/s theoretical?
Link is 8b10b encoded. So it's 10:1 of bits to bytes conversion of link rate.
3Gb/s --> 300MB/s in theory.
---
Yep. Forgot about that... was forgetting about the 2-bits of overhead,
so was using 3Gb/8/(1024*1024) -> 357.6, which I rounded down to 350...
but forgot about the 10/8 encoding (just as I get rid of that conversion
habit from modem days, now I have to remember it as a special case for
SATA...:-) ).
For MB/s, it depends on the SATA controller. Don't expect more then
225-235 MB/s per port. At least one sata_sil3124 chip (3126?) is buggy
and won't do more than 120MB/s read for all ports (170 MB/s write).
See linux-ide archives for discussion on this.
---
That's horrible! I'd definitely call that a bug. Right now,
the fastest I'm getting on my single ATA's is 70-80MB/s. I could
get that per/ATA port. So 120MB read for 4 SATA ports would be
a giant step backwards (170MB/s write? write faster than read?)
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