Re: Chassis E-Sata connection to MB
- From: "TVeblen" <killtherobots@xxxxxxx>
- Date: Sat, 28 Feb 2009 07:34:15 -0500
"Paul" <nospam@xxxxxxxxxx> wrote in message
news:go9vvd$kia$1@xxxxxxxxxxxxxxxxxxxxxx
TVeblen wrote:
My head hurts. A couple of the cases I'm looking at have front panel
E-Sata ports. I am looking at the X58 motherboards and I don't see any
that have an E-Sata header on the motherboard (most have E-Sata rear
panel ports). But I don't see how you connect the chassis' E-Sata port.
Has anyone done this, or is the front E-Sata port before it's time?
For instance:
The Biostar T-Power X58 motherboard lists in it's specs under "Storage" :
6 x SATA2 Connector (Raid 0,1,5,10)
2 x eSATA2 Connector (Raid 0,1)
But when I look in the motherboard manual I see no extra connectors or
headers shown other than the 6 SATA2. Am I missing something?
Third stack from the left, consists of two E-SATA connectors. These are
the rear E-SATA ports, ready to use, and are likely driven by the
JMB363 separate chip.
http://images17.newegg.com/is/image/newegg/13-138-135-S02?$S640W$
The ICH10 also supports ESATA. This is from the datasheet 319973 for ICH10
family.
"ICH10 supports external SATA. External SATA utilizes the SATA
interface
outside of the system box. The usage model for this feature must
comply
with the Serial ATA II Cables and Connectors Volume 2 Gold
specification
at www.sata-io.org. Intel validates two configurations:
1. The cable-up solution involves an internal SATA cable that connects
to the SATA motherboard connector and spans to a back panel PCI
bracket
with an e-SATA connector. A separate e-SATA cable is required to
connect
an e-SATA device.
2. The back-panel solution involves running a trace to the I/O back
panel
and connecting a device via an external SATA connector on the
board."
To use one of the ordinary looking Intel motherboard SATA ports, for
ESATA,
you'd use an adapter like this. Or use that SATA to ESATA front panel
thing.
The essential ingredient, is that the transmit and receive voltage levels,
include enough budget for the longer allowed ESATA cable.
http://www.newegg.com/Product/Product.aspx?Item=N82E16816111064
When purchasing external ESATA cabling for outside the computer, and using
the Intel ICH10 ports for such a purpose, it might be best to limit
overall cable length to 1 meter. The Intel datasheet doesn't meet the
500mV
minimum transmit level, which may not be a problem. To be safe, you can
limit the length of cabling used on the front setup.
+--------------+
(Rear X T-force |
Ones) X X58 | Computer case wiring,
+-------------+
| | SATA to ESATA, front panel External ESATA
cable | |
| ICH10R --->X------------------------------X
X-----------------------X X Drive |
| X
| Enclosure |
| | <---------------- ~ 1
meter -----------------------> | |
+--------------+
+-------------+
The Jmicron JMB363 might be what is driving the "real" ESATA ports
on the I/O area at the back of the computer. They're supposed to support
Gen1m and Gen2m (ESATA 150 and ESATA 300), and if you wanted to use
a 2 meter cable there, that might be OK. Since there aren't electrical
specs available, to check the transmit and receive voltage levels, it
is hard to verify how "real" the ESATA ports are.
http://www.jmicron.com/Product_JMB363.htm
E-SATA is a slight tweak on voltages, allowing higher loss via a longer
cable. So it shares much with ordinary SATA. If you are unsure of the
authenticity of the electrical interface, the best solution is to use
shorter cables with it.
http://en.wikipedia.org/wiki/E-sata#External_SATA
"eSATA, standardized in 2004, provides a variant of SATA meant for
external connectivity. It has revised electrical requirements in
addition to incompatible cables and connectors:
* Minimum transmit potential increased: Range is 500?600 mV instead of
400?600 mV.
* Minimum receive potential decreased: Range is 240?600 mV instead of
325?600 mV.
* Identical protocol and logical signaling (link/transport-layer and
above),
allowing native SATA devices to be deployed in external enclosures
with
minimal modification
* Maximum cable length of 2 metres (6.6 ft) (USB and FireWire allow
longer distances.)"
The higher minimum transmit (500) and lower minimum receive (240)
sensitivity,
is what gives a longer cable (loss) budget.
Paul
That is great info. Very helpful.
Yes, the Jmicron JMB363 controls the two rear Esata ports, that was never in
question. Just the chassis front panel esata connection. I had considered
the idea of running a cable from one of those back ports to the front panel
connector but didn't consider the electrical issue. Good point. The Gigabyte
EX58 UD4P motherboard comes with a similar product as the Sans Digital (2
Esata ports on an expansion slot) but theirs also has a separate electrical
connection to the power supply. I thought that seemed primitive, but maybe
not. But running a cable in and out of the back of the case is pretty
primitive too. Maybe I should just reconsider the chassis.
It is the hot swapping that creates the issue here (for me). No problem on
the two rear ports that are on the Jmicron JMB363, it meets spec. But if I
connect that front case esata to one of the ICH10R SATA2 ports can you still
safely hot swap an external drive? I'd hate to fry the Southbridge with a
static discharge because proper grounding isn't present for the possibility
of hot swapping drives.
.
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