The current x86 architecture suffers from the `80 constrains. In the last several years the key players in the IT world tried to impose several standards that were supposed to improve the peripherals performance. Current CPUs are very fast, the memory speed (one of the major bottlenecks several years ago) was also improved, but not many things were done in order to improve the storage system performance. Although the IDE standard evolved over time, it’s pretty clear that a radical change has to be done. SCSI designers didn't hesitate to change the electrical and the mechanical specifications of their technology, but the impact of these changes was minimal on the market. SCSI is targeted to the business market, where any change is welcomed as long as it provides a better performance. Business customers are not interested to use the old drives in the new computers, but for regular users it is often important to deal with a backwards compatible standard. For this reason manufacturers made a lot of efforts to improve the IDE standard and to maintain the compatibility with the old drives.

Today we will take a look to the new SATA standard, the new comer on the storage market. In order to test the features of the new standard we have several products from two very well known companies in the storage field: High Point Technologies and Promise Technology.

What to expect from SATA?

SATA standard was developed because most of the problems inherited by parallel ATA over time could not be solved by a parallel ATA facelift. The main technological difference between the old standard and the new standard is the way how data is transferred from controller to peripherals. With parallel ATA the data bits were transferred in parallel and the information was repacked at the end. The Ultra ATA standard uses a 16 bit parallel connection in which the clock signal is sent with the data.
In the past years it became obvious that the serial communication can be done in a more flexible and reliable way than the parallel communication. It’s technologically feasible to design high speed serial controllers because the serial communication is less susceptible to external noise and synchronization problems. As you know, the length of the parallel ATA cables is limited because it was impossible to maintain a reliable communication with higher length cables. The parallel data cables need a lot of wires and therefore they create a lot of routing problems. Another stressing issue for manufacturers is that parallel ATA requires a voltage of 5V that can no longer be sustained by the current chipsets.
Serial ATA overcomes all these limitations and provides new features. Find below a short list of SATA advantages:

• 1m cable length limit, makes possible external storage devices (SCSI like)
• low pin count, small sized connectors, maximize airflow
• point-to-point connectivity, no more master and slave devices, easy termination
• very low voltage required
• easily scalable (2.4 Gbits/s scheduled for 2004)
• plug and play compatible
• light protocol overhead
• much better data integrity (please note that originally the parallel ATA had no error checking/correction capabilities)

Fortunately the list of SATA advantages over parallel ATA is much larger. I am not going to discuss all the advantages of SATA without providing some practical examples, although from the theoretical point of view there are a lot of things that can be commented.