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[help] SATA 1,5 GB vs SATA 3GB performance

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September 6, 2006 11:17:14 AM

I will buy a mobo that only support SATA 1,5GB
so i want to know how bad is SATA 1,5GB compared to SATA 3GB
only speed or what?

any suggestion/link would be appreciated...
thx
September 6, 2006 11:38:12 AM

SATA 1.5 isn't significantly slower than SATA 3. The actual, physical speed of the drive still can't get close to the 1.5GB/s limit, let alone 3GB/s.

The difference is in some of the other features which SATA 3 supports, such as TCQ/NCQ - but these make almost *no* improvement in non-server roles (have a look at storagereview.com if you don't believe me)...

SATA 1.5 is not bad at all. Don't fret if you can only buy one that supports that.
September 6, 2006 11:52:26 AM

Quote:
SATA 1.5 isn't significantly slower than SATA 3. The actual, physical speed of the drive still can't get close to the 1.5GB/s limit, let alone 3GB/s.

The difference is in some of the other features which SATA 3 supports, such as TCQ/NCQ - but these make almost *no* improvement in non-server roles (have a look at storagereview.com if you don't believe me)...

SATA 1.5 is not bad at all. Don't fret if you can only buy one that supports that.



i see....
can SATA 3GB/s HD used in mobo that only support SATA 1,5GB/s (of course with 1,5GB/s speed) ?
im affraid few years later ... it will be difficult to buy new SATA 1,5GB/s .......because all shop just sell SATA 3GB/s ......

thank you
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September 6, 2006 12:14:21 PM

Yes. SATA is 100% backwards compatible and forwards compatible.

If you use a SATA 3 disk on a SATA 1.5 controller, it will run fine - at SATA 1.5 speeds.
If you use a SATA 1.5 disk on a SATA 3 controller, it will run fine - at SATA 1.5 speeds.

SATA is a very sane standard!
September 7, 2006 1:06:08 AM

Quote:
Yes. SATA is 100% backwards compatible and forwards compatible.

If you use a SATA 3 disk on a SATA 1.5 controller, it will run fine - at SATA 1.5 speeds.
If you use a SATA 1.5 disk on a SATA 3 controller, it will run fine - at SATA 1.5 speeds.

SATA is a very sane standard!


There are some cases where to use a 3.0 Gb/sec drive on a 1.5 Gb/sec controller where a jumper must be installed on the hard drive. It depends on the SATA controller. The drive and the controller are supposed to auto-negotiate to determine what speed to run at (just like a 10/100/1000 Ethernet switch will negotiate with the Ethernet card to determine what speed to run at), but some older SATA 1.5 Gb/sec controllers do not support the auto-negotiation.
September 7, 2006 5:17:52 AM

Quote:
Yes. SATA is 100% backwards compatible and forwards compatible.

If you use a SATA 3 disk on a SATA 1.5 controller, it will run fine - at SATA 1.5 speeds.
If you use a SATA 1.5 disk on a SATA 3 controller, it will run fine - at SATA 1.5 speeds.

SATA is a very sane standard!


There are some cases where to use a 3.0 Gb/sec drive on a 1.5 Gb/sec controller where a jumper must be installed on the hard drive. It depends on the SATA controller. The drive and the controller are supposed to auto-negotiate to determine what speed to run at (just like a 10/100/1000 Ethernet switch will negotiate with the Ethernet card to determine what speed to run at), but some older SATA 1.5 Gb/sec controllers do not support the auto-negotiation.

ok. its clear now

thank you very much pals.
September 7, 2006 8:05:54 AM

7200 rpm to 10000 or to 15000rpm spin will give more significant results.

Cache memory can give significant results too.
September 9, 2006 3:33:55 AM

Zero performance difference until individual drives start exceed 150 MB/s which won't be happening for quite very long time.
September 9, 2006 3:48:41 AM

you guys got your terminology screwed up.

sata 1 ='s 1.5
sata 2 ='s 3.0

start saying sata 3 you're gonna make people think there is a sata 3 so when they go and mention "hey i need a sata 3 cable" the guy is going to stare at you like you're a retard and go "what? you mean sata 1 or 2?".

please please please get the terminology right! It's there for a reason!

Quote:
SATA 1.5 isn't significantly slower than SATA 3. The actual, physical speed of the drive still can't get close to the 1.5GB/s limit, let alone 3GB/s.

The difference is in some of the other features which SATA 3 supports, such as TCQ/NCQ - but these make almost *no* improvement in non-server roles (have a look at storagereview.com if you don't believe me)...

SATA 1.5 is not bad at all. Don't fret if you can only buy one that supports that.
September 9, 2006 3:53:38 AM

it makes the drive signifantly hotter also. So the drive life expentency is much less. Higher RPM drives are really for developers/workstations or servers.

Quote:
7200 rpm to 10000 or to 15000rpm spin will give more significant results.

Cache memory can give significant results too.
September 9, 2006 4:09:45 AM

oh god i gave up on tryign to explain the difference between big B and little b. lol!

GB ='s gigabytes Gb ='s gigabit/

if you do the math 1.5Gb divide that by 8 gives you bytes. it's actuall 0.1875GB/s so if you do the math thats 187.5MB/s theorhetical bandwidth.

But of course that just flies over peoples heads

Quote:
And it's even more annoying when one incorrectly uses GB/s instead of the actual which is Gb/s.
September 9, 2006 5:14:55 AM

FYI There is no such thing as SATA 1 and SATA 2 hard drive they are all just pain old SATA drives.

If you want to loosely refer to all drives implementing any feature added by the SATA II specification as SATA 2 then every SATA drive ever sold ends up being a SATA 2 drives, and SATA 1 refers to something that only existed as a prototype form and was never released to consumers.

Manufactures who use those terms are just making up imaginary standards.

Don't like it? complain to the SATA IO Board who gets to have the final word on such things.

---

SATA 1.5 Gbps doesn't equal 187 MBps because 2 out of 10 bits are parity bits. So you have an actual maximum transfer rate of 150 MBps.

Yes the Gbps number includes the parity and data bits while the MBps rating includes just the data bits.

Why the inconsistency? Because people are willing to tolerate a little inconsistency as long as they get to nice numbers like 1.5 and 150 rather than nasty ones like 1.2 or 187.

---
BTW that doesn't mean that a 150 MB gets moved in one second.

The M in MB = 1024^2 bytes and the M in MBps = 1000^2 Bytes per second.

The (often ignored) convention is to switch to standard metric prefixes whenever a unit of measurement other than a byte is involved.

So 150 MBps should mean 143 MB gets moved in one second.

You can add an "i" to avoid confusion (150 MBps = 143MiBps), but it usually just adds it.
September 9, 2006 5:27:10 AM

Quote:
if you do the math 1.5Gb divide that by 8 gives you bytes. it's actuall 0.1875GB/s so if you do the math thats 187.5MB/s theorhetical bandwidth.


8b/10b ECC encoding reduces availible bandwidth to 150MB/sec, or 146MiB/sec, despite the 1.5Gb/sec signaling rate.

But to the OP, the *only* way SATA 3Gb, or SATA II, or whatever you want to call it, matters if if you are:

1: Using an external device over SATA that is a RAID array internally. These are rare, and the ones that I have seen are unlikely to top 150MB/sec anyway.

2: Using an SATA port multiplier to attach 3 or more disks to an SATA port. These work like hubs for USB, and are also very rare. If you have one, you'd know about it.

3: Using a pointlessly overpriced static device with hardly any storage capacity that would be better connected directly by PCI-E x4 or more anyway, like Gigabytes I-Ram device.

Add to this that even alot of *onboard* SATA ports hang off a PCI, or sometimes PCI-E x1 interface, (at 133MB/s and 250MB/s respectively) and you realise that even in those rare circumstances its kinda redundant.

I dont think a single SATA drive, even a Raptor, is going to get even 100MB/s sustained transfer. I actually think its quite a bit less than that, but I'm sure someone else has exact figures. As such, the SATA interface is NOT the slowest part of the system, so changing to SATA2 is like expanding a 100ft section of a 3 lane highway to 20 lanes and wondering why traffic doesnt speed up.
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