How to Connect Hard Drives
One thing that you always have to remember about your hard drive is that it doesn't matter how fast the drive is, it can only transfer data as fast as its interface will let it. That was one big reason for the move to SATA, it was simply faster than the previous standard.
What is the Difference Between PATA and SATA?
Both interfaces use different forms of IDE, or integrated drive electronics. This means that the drive controller rests in the hard drive itself, rather than on the motherboard. However, despite this commonality, the term IDE only refers to PATA storage solutions and not SATA.
- PATA: Parallel Advanced Technology Attachment uses a 40-pin connector and works by sending multiple bits of data across the interface in parallel. The first generations used 40 conductors, while speeds past 66 MB/sec required 80-conductor cables.
- SATA: Serial ATA uses a serial interface which sends fewer bits per transfer but also sends them at much higher frequencies. The end result is that even though serial interfaces are often less efficient in theory, a SATA HDD is faster in practice than a PATA HDD.
How Many Kinds of SATA Are There?
There are three main SATA revisions on Hitachi Deskstar and other HDDs. Each revision reflects an overall increase in performance and capability from earlier versions. One major reason for increasing hard drive interface speeds is that the greater the storage capacity, the more speed you need to transfer the data in a reasonable period of time. Putting a TB drive on an ATA 33 interface would severely hobble the drive.
- SATA I: The first iteration dropped the signal voltage from 5 Volts to 250 millivolts, as well as increasing the transfer rate from 133 MB/sec to 150 MB/sec.
- SATA II: The successor introduced NCQ, or native command queuing which improved the overall efficiency as well as doubling the transfer speed to 3.2 Gbps or 300 MB/sec.
- SATA III: This revision maintained the performance advantages of SATA II, while doubling speeds again to 600 MB/sec.
Choosing a Hard Drive
One of the first things to decide on when looking for a hard drive is capacity. For many users 250 GB is a good minimum, while some may want 1 TB or even more. While many users have shifted to SSDs, a 7200 RPM rotating hard drive can provide excellent performance and Hitachi internal hard drives are often available with more storage than a solid-state alternative. Disk performance relies on more than just the interface; both spindle speed and onboard cache play a role in boosting hard disk drive transfer rates.
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