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Re: Problem with eSATA Port Multiplier

Ron Johnson put forth on 10/1/2010 5:28 PM:
> On 09/30/2010 10:13 PM, Stan Hoeppner wrote:

>> Have you tried more than one eSATA cable?
> Only have one.

Pick up a new one from a retailer that'll give refunds on returns no (or
few) questions asked.  If the new cable doesn't fix the problem get your
money back.

>> Can you please post every bit of information you can find WRT the PMP
>> device and the drive enclosure?  Are they on in the same?  If you have
>> pictures of the devices that would be very helpful, so I can get an idea
>> of what plugs into what, and where, and how.
> http://members.cox.net/ron.l.johnson/PMP_innards.jpg
> http://members.cox.net/ron.l.johnson/PMP_front.jpg
> http://members.cox.net/ron.l.johnson/PMP_rear.jpg

Ok, so the 4 drive SATA JBOD box has a small cheap hotswap backplane
containing the port multiplier chip.  If the problem isn't the cable,
it's likely the backplane itself.  I've read many horror stories on the
Linux-RAID and XFS lists about cheap backplanes.  Direct connecting the
drives to the controller fixes the problem in over 90% of the cases I've
seen.  And it's not just "cheap" backplanes that suffer these problems.
 I've read cases of reputable whitebox backplanes (SuperMicro for
example) having problems.  And it's almost always "active" backplanes
that fail--those with with a PMP or I2C chip, or both.  Passive
backplanes rarely causes problems, and if they do, they're defective out
of the box.  Active backplanes can die over time.  Cross your fingers
and hope it's the cable.

I forgot to ask earlier:  is this JBOD enclosure a recent addition, or
was it working fine for eons and all of a sudden crapped out?


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