A
a.h.
What technical differences are between SATA and ATA?
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I
IDIDIT
What technical differences are between SATA and ATA?
Besides marketing hype not much performance difference. The power
cable connection and the flat info cable is much more narrow than the
80 wire flat ribbon one. A word of caution, the connector guide or
holder on the drive for the info cable was/is brittle on one of my
drives and broke off with a bit of careless cable removal, not pulled
out straight. NOT covered by warrenty! = useless drive!
J
J. Clarke
a.h. said:What technical differences are between SATA and ATA?
Mostly hype.
SATA sends data one bit at a time down a single pair and receives it the
same way, vs 8 bits in parallel for PATA. The SATA interface has a
transfer rate of 150 or 300 MB/sec vs 133 for the fastest version of PATA,
which is moot because there are no drives that can fill even a 100 MB/sec
channel. SATA uses a thin cable with connectors only slighly more fragile
than DDT-affected eggs, PATA uses a wide ribbon cable with relatively
durable connectors. SATA is specified to support hot-swapping of drives
(in practice that doesn't work too well yet) while PATA does not. One can
buy 10,000 RPM drives with PATA interfaces but not with SATA.
That pretty much covers it I think. If you want details of signal levels
and encodings and command sets and whatnot you'll need to dig up a copy of
the specs.
B
Bob Willard
a.h. said:What technical differences are between SATA and ATA?
SATA = Serial ATA; (P)ATA = Parallel ATA. The SATA cable is much
narrower than the PATA cable and, therefore, less likely to block
air flow in a case. The SATA cable (by spec) can be longer than
the PATA cable and, therefore, allows more freedom in placing HDs
w.r.t. the MB in a full tower case. SATA is less sensitive to
crosstalk and, probably, RFI; but I won't argue about whether or
not those issues are of practical importance. SATA supports one
device per cable, while PATA supports two; I contend that this
makes SATA better, but others may think the opposite.
D
Derek Baker
J. Clarke said:Mostly hype.
SATA sends data one bit at a time down a single pair and receives it the
same way, vs 8 bits in parallel for PATA. The SATA interface has a
transfer rate of 150 or 300 MB/sec vs 133 for the fastest version of PATA,
which is moot because there are no drives that can fill even a 100 MB/sec
channel.
True for a single drive, but PATA takes two per cable. A couple of Raptors @
70MB/sec each would we restricted by ATA-133.
J
John Doe
J. Clarke said:a.h. wrote:
SATA sends data one bit at a time down a single pair and
receives it the same way, vs 8 bits in parallel for PATA. The
SATA interface has a transfer rate of 150 or 300 MB/sec vs 133
for the fastest version of PATA,
Is that because of shielding on the serial cables? Otherwise I
can't imagine why the parallel interface would be limited.
N
Nick
Is that because of shielding on the serial cables? Otherwise I
can't imagine why the parallel interface would be limited.
Actually, there are 16 data bit on a PATA cable.
Transmiting data in parallel is much more complicated than in serial.
That's why Sata is faster.
Nick
J
J. Clarke
John said:Is that because of shielding on the serial cables? Otherwise I
can't imagine why the parallel interface would be limited.
It's because the SATA standard calls for 150 or 300 as the standard
signalling rates, while the PATA standard calls for 33, 66, 100, or 133,
and so that's what the hardware is designed to do.
J
J. Clarke
Derek said:True for a single drive, but PATA takes two per cable. A couple of Raptors
@ 70MB/sec each would we restricted by ATA-133.
(a) you're not _required_ to use 2 per cable
(b) that 72 MB/sec is for sequential transfers on the outermost zone. In
the real world you'd hardly ever see that transfer rate even with an
infinite-speed interface.
E
Eric Gisin
PATA's udma-133 operates at 33MHz, which is pretty high for SE bus. SCSIJohn Doe said:Is that because of shielding on the serial cables? Otherwise I
can't imagine why the parallel interface would be limited.
Ultra is only 20MHz. You need LVD and 80-pin connectors to go higher.
C
CJT
<snip>John said:Is that because of shielding on the serial cables? Otherwise I
can't imagine why the parallel interface would be limited.
My two bits:
At high speeds, small phase/timing differences between the parallel
signals can cause errors, so the detection/synchronization circuitry
gets complex. Complex circuitry introduces its own delays. The specs
also have to allow sufficient margin for all the needed parallel
signals to arrive within an acceptable window, which limits the usable
overall bandwidth.
D
Derek Baker
J. Clarke said:(a) you're not _required_ to use 2 per cable
No, but you might have to.
(b) that 72 MB/sec is for sequential transfers on the outermost zone. In
the real world you'd hardly ever see that transfer rate even with an
infinite-speed interface.
True. Though the Raptor's already at 61 MB/sec average sustained.
D
Derek Baker
John Doe said:Is that because of shielding on the serial cables? Otherwise I
can't imagine why the parallel interface would be limited.
[snipped]
The PATA interface is limited by crosstalk
J
J. Clarke
Derek said:No, but you might have to.
True. Though the Raptor's already at 61 MB/sec average sustained.
Which means sequential transfers. Not random access, which is what usually
happens in the real world.
R
Rod Speed
Nick said:Actually, there are 16 data bit on a PATA cable.
Transmiting data in parallel is much more complicated than in serial.
That's why Sata is faster.
Utterly mangled.
O
Odie Ferrous
a.h. said:What technical differences are between SATA and ATA?
SATA sucks.
Marketing ploy.
Crappy connectors.
Absolutely NO increase in performance in the real world.
Is that technical enough?
Odie
D
Derek Baker
J. Clarke said:Which means sequential transfers. Not random access, which is what
usually
happens in the real world.
Agree with usually. Would be different for someone pushing really big files
around.
When I upgrade soon to SATA drives, I'm not expecting any perceptible
performance increase, though the thin cables will be nice.
D
Derek Baker
Odie Ferrous said:SATA sucks.
No, but not radically better than PATA.
Marketing ploy.
Crappy connectors.
Absolutely NO increase in performance in the real world.
True, but increases headroom for the future. Agree that change to 300 MB/sec
unnecessary.
N
Nick
Actually, there are 16 data bit on a PATA cable.
What ? The 16 bits ? Or the serial communication ?
Utterly mangled.
What ? The 16 bits ? Or the serial communication ?
R
Rod Speed
What ? The 16 bits ? Or the serial communication ?
The