[DC LoCo] Resolve External Drive Issues With JMicron Controllers

[Michael Haney]

For those having issues with 8 drive external USB3 HDD enclosures that use
the JMicron controller, I've found a fix.

The issue that occurs involves a certain firmware used in the NEC/Renesas
USB 3.0 controllers found on certain motherboards used with external drive
enclosures that use a JMicron controller. NEC/Renesas appears to be the
only source for USB3 controller chipsets, as far as my research goes. The
enclosures experience random USB disconnects, even when being used, and
then remount after a few seconds. Certain server software like AFP, if you
have Macs on your network, can cause the file systems to be remounted as
read-only. I encountered this with the Mediasonic 8x Probox external
USB3/eSATA HDD enclosure. This also occurs with any other external drive
enclosure with the JMicron controller.

Many of the JMicron-based external drive enclosures support both USB and
eSATA. Switching to the eSATA interface resolves the issue. If you are
using an enclosure with more than 4 HDD you need an eSATA card that
supports up to 8x or more multiplexing. The Mediasonic 8x Probox is known
to work with the Addonics 4 Port eSATA II RAID Controller
http://www.amazon.com/gp/product/B002O4FYR4 and this works without
additional software in Ubuntu 12.04. This should also work with any
JMicron-based external enclosure that also supports both USB and eSATA.

I've discovered that JMicron controllers are crap, and that many of these
enclosures use two controllers. One for USB and the other for eSATA.

-- 
Michael "TheZorch" Haney
https://sites.google.com/site/thezorch/

"Faith is not faith in anything. Faith is the trust, without any proof or
supporting evidence, that all is well and that all will be well."
-Q'uo

"When you change the way you look at something, what you look at changes."
-Ancient Wisdom

Free Your PC, Open Your Mind www.ubuntu.com
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