On 3/6/2011 1:51 PM, Orvar Korvar wrote:
And 6Gbit SATA card needs a driver?
Yes.
You are confusing physical layer (connections and cables) with
chip-level processing. Physical layer simply describes how the
electrical signals are sent, and has nothing to do with the actual
*content* of those signals.
Each of the following requires some sort of chipset - this chipset
interprets the information it gets from the computer, and converts it
into the appropriate protocol. In general, a new PROTOCOL will require
a new chipset. Certain chipsets will provide backwards compatibility
(i.e. something handling a 3.0 protocol will likely also understand 2.0
and 1.0 of that particular protocol), but there is no forwards
compatibility (i.e. a 2.0 chipset can't understand 3.0 protocol).
SATA
IDE
SCSI
FibreChannel
USB
(and many others).
Chipsets require drivers. Physical layer changes do not.
When determining what protocol is spoken over a physical connection
between a host controller and a drive (or other peripheral), you look
for the highest common denominator - thus, a 2.0 controller will speak
2.0 when talking to a 3.0 peripheral, but will speak 1.0 when talking to
a 1.0 peripheral.
When wondering whether a device is a chipset or a physical layer change,
consider this: does the device actually change the information being
transported through it, or does it merely change the electrical form of
the message?
Thus, the following would only change the electrical form:
SAS/SATA port multiplexer/replicators - they don't change the
information, merely create a 1-to-many electical signal.
eSATA - it changes the physical connector and cable, but doesn't make
any other information change
SCSI Ultra2 -> Ultra320 cables - once again, merely the electrical
signal is changed, not the information format
FC multimode vs singlemode connectors - defines what type of laser
signal is used to send the FC packets, and thus is just a electrical format
To be perfectly honest, there is one category that is slightly
confusing: protocol translators, often called "bridges". You most often
see this in the "SAS to SATA bridge", though many Host Bus Adapters also
contain a chip on them that does PCI-E to <something> translation.
These items are "magic black boxes" - they take an input signal, and
"magically" convert it to some other. They do this independent of any
OS or outside control, and thus, don't need a driver. Bridges don't
alter the information content of the signal, but do alter the protocol
being used - they act as super-translators.
--
Erik Trimble
Java System Support
Mailstop: usca22-123
Phone: x17195
Santa Clara, CA
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