From a posting by Daniela Engert (Dani) on comp.os.os2.ecomstation:

TOPIC: SATA or IDE Re: SATA or SCSI?
http://groups.google.com/group/comp.os.os2.ecomstation/browse_thread/thread/59d6f4002be77f2f?hl=en
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== 1 of 2 ==
Date: Sat, Mar 10 2007 6:58 pm 
From: Daniela Engert  


Mat Nieuwenhoven wrote:
> > :>>> Don't. IDE CD, and DVD, drives are just fine, and, they are 
> > :>>> available,
> > :>> 
> > :>> With their attendant master versus slave issues.

Which are basically none.

> > :>>> SATA is really the only option for new hard drives, and, it
seems 
> > :>>> to work well, as long as you use the latest Dani drivers 
> > :>>> (highly recomended anyway).
> > :>
> > :>I am under the impression that SATA is a serial version of ATA, a 
> > :>parallel implementation of ATA is IDE?

The parallel version of ATA is PATA.  IDE, EIDE ore the like are 
obsolete (marketing) names.

> >  Since no hard drive can move 
> > :>data faster than IDE can deliver it, SATA advantages are just
marketing 
> > :>hoopla, no?

Pardon? About every current-generation disk can deliver data faster than 
ATA-1/2/3/4 specced PATA interfaces can handle, and those cover the 
better part of the lifetime of PATA.

> > Serial ATA is (as transfer mechanism) faster than parallel ATA.

SATA is an implementation of ATA with a completely different physical 
layer, which happens to be faster than the one used by PATA . The SATA 
physical layer is so good that the SCSI ANSI committe (T10) (almost 
instantly) dropped further development of faster parallel interfaces, 
rendered the parallel interfaces obsolete and picked the SATA phy 
instead: SAS was born.

> >SATA2 is
> > specced for 3 Gbit/s (375 Mbyte/s), PATA max 133 Mbyte/s . 

There is no such thing as SATA2. For details have a look at 
http://www.sata-io.org/namingguidelines.asp. SATA spec 2.0 doesn't even 
imply 3.0Gb/s wire speed. And, btw, 1.5Gb/s translates into 150MB/s, 
3.0Gb/s translates into 300MB/s due to the 8B10B coding at the physical 
layer.

Besides the speed at the physical interface layer one has to take the IO 
bus limitations into account. With regular PCI you get hardly anything 
faster than 100MB/s. This is the reason why the professional world has 
moved on to PCI eXtended (PCI-X). On desktops (and soon workstations and 
servers as well) PCI is mostly obsolete and replaced by PCI express 
(PCIe) which has got 250MB/s each in both directions concurrently in its 
slowest implementation (PCIe x1).

> > If you transfer
> > from the cache of the disk (frequently 8M or now nowadays) that
makes a
> > difference. I think I read a short while ago that Fujitsu has a
new drive
> > which gets well above the 1.5 G/s transfer speed of SATA1 . Of
course, from
> > the disk platter you're not getting that speed (70 Mbyte/s or so
on fast
> > drives).

Almost any modern SATA disk can go faster than 1.5GB/s during host  
disk cache transfers. From my machine here:

Controller:1  Port:A400 IRQ:0B  Status:OK BusMaster Scatter/Gather
   NVidia nForce SATA host (10DE:037F rev:A2) on PCI 0:5.0
  Unit:0 Status:OK SMS:16 LBA BusMaster 3.0GBit/s BPB
   Model:ST3320620AS                             3.AAC

Hard disk 1: 255 sides, 38913 cylinders, 63 sectors per track = 305242 MB
Drive cache/bus transfer rate: 194129 k/sec
Data transfer rate on cylinder 0   : 77009 k/sec

> > Besides, SATA2 has command queuing, and (with a different
connector and
> > cable) eSata (external sata), allowing external drives up to 2m away. 

Not to mention port multipliers, which make - in conjunction with eSATA 
- really interesting external storage solutions!

Ciao,
   Dani
 
Regards,
Mike






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