On Aug 24, 2007, at 8:19 PM, Tejun Heo wrote:
Hello, Rusty.
Rusty Conover wrote:
I have some interesting results.
I had a pair of Seagate 250 GB SATA disks (models below) and tried
those
out rather then the WD's. At the 1.5 gbps rather they appear to
work
just fine both being on the same PMP, at 3.0 gbps they timeout
just like
the other disks did. Possibly, the code isn't detecting the max
rate of
the disks correctly since these drives only do 1.5 and it
attempted to
do 3.0 gbps?
Hardware PHY layer is fully responsible of 1.5/3.0 negotiation. The
driver can limit the maximum it can go but doesn't have much say in
the
actual negotiation.
Unfortunately, some SATA PHY combinations have problems at 3.0bps. I
saw quite a few weird cases. e.g. marvell PMP can't detect older
Seagate drives on 3Gbps and can't talk to a first gen Maxtor even at
1.5. I'm still not quite sure how to solve this. Once detected,
libata
EH will do the right thing and speed down to 1.5 after a few
transmission errors but it's a bit trickier before detection. It's
probably not worth driving fan-out ports at 3.0Ghz in the first
place so
maybe limiting PMP fan-out ports to 1.5 by default can alleviate most
situations. Oh well, users won't be happy tho.
Have you found that drives can be picky if they will work or not with
PMP ports?
As I said above, yeap. Not only PMPs some host PHYs do that too.
I'll be trying to get a bunch of different drives to replace the ones
that don't work with PMP.
Yeah, that will be the easiest way out for the moment.
Thanks.
Hi Tejun,
After a lot of fiddling with speed limiting and different drives, I
still couldn't avoid the port resets under high load. The new
seagate drives did work okay when both of them were paired in two PMP
ports, but when I assembled the full array under high load one or the
other PMP's would timeout and reset. Of course this might be okay
for some people, who don't put a high amount of load on their drives
but it isn't going to work for me.
After all I decided to send back the piece of hardware and just
switch to a solution that has the SATA ports on the main board.
Thanks for you help trying to get all of this working, I probably
just had a bad adaptor card or drive enclosure.
Thanks again,
Rusty
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