Even if you've never heard of a PATA drive, you're probably more familiar with parallel ATA technology than you think. PATA drives have been around for decades, but no one referred to them as PATA drives until recently. They were always known as IDE drives.

The only real change to IDE buses over the years was that the bus speed got faster. Remove an IDE hard drive from a computer made in 1992 and you'd see the drive conforms to the 3.5-inch form factor still in use today. That 15-year-old drive would also have the same connectors as hard drives made today. In fact, you could plug that old drive into a new computer and read the data off of it (assuming that a drive that old were still functional).

But PC makers wanted to get away from using dated PATA technology so they could take advantage of new technology without being limited by the constraints caused by maintaining backward compatibility with these "ancient" IDE devices. Hence, SATA was created.

SATA drives are basically identical to PATA drives aside from the interface that connects the drive to its controller. This means that comparable SATA and PATA drives perform identically in terms of read and write speeds. However, SATA drives have faster transfer speeds than PATA drives.

For years, PATA drives had a maximum transfer speed of 100MBps. recently, that ceiling has been increased to 133 MBps. By way of comparison, SATA drives have a transfer speed of 1.5 GBps (roughly 150 MBps). And a newer technology called SATA2 supports transfer speeds of 3.0 GBps. incidentally; SATA2 drives can be used in machines with SATA controllers. The drive will just be limited by the controller's 1.5 GBps capacity.

Faster transfer speeds are not the only advantages to using SATA. SATA drives use smaller power cables and data cables than PATA drives. These smaller cables take up a lot less space in the computer case, and promote better air circulation within the case.

Why does this matter? The first reason why the transition to SATA is important is because it might soon mean that hard drive replacements are impossible or impractical on some workstations that are just a few years old. PATA hard drives are still available, but they are starting to disappear. In fact, they're quickly disappearing. Eventually it will be impossible to replace a PATA hard drive that has gone out.

SATA controllers exist that can be plugged into PCI slots, but this does little good if the PCI slots have all been filled with other devices.

There's another reason why the transition is important. Down the road, it could make data recovery much more difficult. Typically data isn't stored on workstations, but some low-end servers do use PATA drives. When a catastrophic failure occurs, it's a common practice to plug the machine's drives into another machine so that the data can be offloaded. However, if the failed machine uses PATA drives and your other machines all have SATA controllers, this won't be an option. Sure, you can always just restore a backup (assuming that a backup exists), but you'll lose any data that has been written to the drive since the time that the backup was made.

If such a failure were to occur today and you did not have any other machines that supported PATA drives, it would still be easy to work around the problem. One option would be to use an external hard drive enclosure that would allow you to plug the drive into a USB port. Another option would be to use another machine's IDE controllers. Even though SATA is the predominant standard for hard drives, most computers still include at least one IDE port that is intended for use with a CD/DVD drive. In a pinch, you can connect a PATA hard drive to this controller in order to access the drive's data.

But don't expect these controllers to exist forever. Manufacturers of computer power supplies have already begun decreasing the number of available standard power adapters in favor of SATA power adapters. This may indicate that in the near future we'll see DVD drives adapted to the SATA interface. At that time, PC manufacturers will likely stop including IDE ports on system boards.

Currently, the only advantage of using SATA over PATA is the reduction of cable clutter inside the cabinet so that more empty space for air circulation. The theoritical rates of data transfer of SATA are never experienced practically.