I'm having a bit of a problem with some SATA drives
in docking stations connected to USB ports.
The problem seems to be unrelated to heavy I/O and
occurs randomly. Once, without the drive even being mounted.
Did this configuration ever work well for you in the past and did
the problem change with any kind of kernel upgrade or
reconfiguration of the drives or cabling?
Unfortunately I've seen this problem way too many times, especially
with multiport Jmicron controlers such as the one that you have.
I've occasonally been able to solve it by changing or reseating the
cabling. Also make sure the drives are firmly seated in the docking
station. On some systems no matter what I do, if I do simultaneous
IO to more than one USB drive I get errors like this (I know you say
it is not IO related). In some cases it works better to use only a
single drive per controller and plug a second drive into a port on a
different usb controller if your system has more than 1. If it
doesn't work in one dock socket, try the other. Some of the
controllers in these multiport USB peripherals just don't work well
with linux drivers or with the usb controller on a particular
computer.
I wish I had a better answer for you, but I think this is a pretty
common problem with this type of commodity hardware. I have some
systems where it seems to work just fine and others where no matter
what I do it won't work.