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Serial ATA question

F

faye

Platinum Member
Hi, today i saw some Serial ATA supported motherboard...

hmm, let me see... "150MB/s transfer rate" is it right?

i have a WD800JB harddrive(which is not SATA support), does it have advantage if the motherboard support SATA?

or what..??

 
That's the interface transfer rate. With IDE not multitasking drives on a single cable (and SATA not allowing more than one drive per cable anyway), it doesn't make a difference. The fastest IDE drives currently have a media transfer rate of below 60 MB/s, hardly making good use of UDMA-66.

regards, Peter
 
There is a theoretical speed and an actual speed.

There are 2 components:
Hard drive
Motherboard/ interface | the way the harddrive connects


If you have a car that can go 60 mph and up to 80 mph in bursts, whats the point of have a speed limit raised from 100 to 133 to 150?
 
Oh and on the note that since the speed doesn't matter *yet* the main benefit of both devices (mobo and HD) supporting SATA is the cable is much smaller than a normal IDE cable.
 
You got a theoretical maximum transfer rate on the interface. Then you have the actual read/write speed of your drive, which is MUCH lower. Now on IDE, headroom on the interface speed is a complete waste, since you can't do anything with it.

Kind of like having a German Autobahn with just one lane and a Volkswagen (Old) Beetle on it.
 
What does SATA buy you?

On a single drive, when you get cache hits, you get the full bandwidth, eg 150MB/s. Most of the new SATA drives have 8MB cache, so this can be a significant increase in performance.

The real advantage comes with a two (or more) hard drive system.
Take, for example, a system running PATA100. Each port (primary and secondary) is limited to 100MB/s. In reality, this is moved down to 89MB/s due to overhead in the protocol. So, if you have two hard drives connected to the same cable, then you are limited to 45MB/s when you are copying files between the two drives.

And no, you don't want to put one drive on one port and the other drive on the other port, because you'll want to put your DVD drive on one of the ports. This will drop your speed down to ATA66 or ATA33 most likely, because that is as fast as the DVD drive can go.

Since there is one cable per drive, you get the full bandwidth on each cable. In a RAID 0 system, the change is dramatic.

HTH.

-Steve
 
Almost right, except that the days are long gone when the slower drive limited the transfer mode of the other drive on the same cable.
 
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