Why is SATA faster than PATA?

[imported_Darthan]

RAID arrays are an excellent reason to use SATA. Having multiple hard drives is generally the reason to use SATA at the moment. Hard drives have gotten fast enough (at least the top end 7200rpm ones and certainly 10,000rpm and up) that having a dedicated channel for each is going to improve performance. Of course, at some point you'll also be able to use SATA for external drives and I think hot swapping is in the spec too, but not usually implemented in consumer equipment. Also, SATA drives are supposed to use 3.3V power which should, someday, allow PSUs to drop the 5 volt rail entirely. The five volt rail used to exist because the processor needed it, now it just exists because that's what drives use for their chips and really old PCI cards use for signalling. There's no good reason for that. We can make drive controllers that use 3.3V quite happily and same with PCIe or PCI-X or just PCI cards too.

 

[Calin]

Originally posted by: sphinx
So the only way people will be able to take adantage of the SATA interface is if it was used in a RAID array.

As it was already specified, NCQ (Command Queueing) could improve the performance for SATA hard drives. However, it will mostly help for the kind of work not usually encountered on the desktop computers, so for a desktop computer SATA will not be so much faster than an ATA66 combo. Anyway, SATA might be designed from the start to eliminate all the size limits that the PATA EIDE encountered until now (512 MB, 2GB, 137 GB are the ones I know of - well, 512MB was more of a software limit than a hardware one).

 

[Peter]

SATA is just a new cable for the same old IDE controller scheme. They're register compatible, in other words, still the same old thing as the original ST506 ISA hard disk controller from the very first PC-AT. (The thresholds were 504 MB, 7.8 and 128 GiB, btw.)
That said, SATA drives usually implement the latest, 48-bit-LBA capable flavor of that controller.