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eSATA Technology
Overview:
As with any new technology, I was a bit fuzzy
about what the advantages of eSATA would be. With a little help
from the
eSATA White Paper, we can take a look at what eSATA is all about.
Using this picture from the eSATA
white paper, you can see some of the major differences between the eSATA
connectors and the standard SATA we are used to.
The external cable connector is a
shielded version of the connector specified in SATA
1.0a with these basic differences:
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The External connector has no “L” shaped key,
and the guide features are vertically offset and
reduced in size. This prevents the use of unshielded
internal cables in external applications.
-
To prevent ESD damage, the insertion depth is
increased from 5mm to 6.6mm and the contacts are
mounted further back in both the receptacle and
plug.
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To provide EMI protection and meet FCC and CE
emission requirements, the cable has an extra layer
of shielding, and the connectors have metal contact
points.
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There are springs as
retention features built into the connector shield
on both the top and bottom surfaces.
The external connector and cable
are designed for over five thousand insertions and
removals while the internal connector is only
specified to withstand fifty.
Most common external storage
solutions use USB and/or 1394. These interfaces are not nearly as fast
as SATA when compared using peak values, and can compromise drive
performance.
USB and 1394 external drives are
ATA drives with a bridge chip that translates from
the ATA protocol to USB or 1394 protocol used for
the connection. These interfaces require
en-capsulation or conversion of the transmit data
and then de-capsulation after the data is received.
This protocol overhead reduces the efficiency of
these host buses, increases the host CPU utilization
or requires a special chip to off-load the host.
The results of
eSATA are dramatic and with no protocol overhead
issues as with USB or 1394. The eSATA storage bus
delivers as much as 37 times more performance. This
ability is perfect for using an array of drives with
performance striping behind the eSATA host port.
Key
benefits of eSATA:
- Up to 6
times faster than existing external storage
solutions: USB 2.0, & 1394
- Robust and
user friendly external connection
- High
performance, cost effective expansion
storage
- Up to 2
meter shielded cables and connectors
In a nutshell, eSATA brings all of
the advantages we are used to from your internal eSATA 3Gb/s connections
to the external device world. At the same time, eSATA has
redesigned the SATA connectors to be more durable and dependable with a
greatly reduced risk if problems related to hot-swapping.
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