How does sata speed correlate with actual transferspeed?

hard drivemotherboardsata

On my motherboard I have "SATA 6Gb/s" ports, but when I transfer I typically get 70+ MB/s. It's a "SATA 6Gb/s" disk.

I think I have the same issues with my old PC I use as a server, but it has "SATA 3Gb/s" speed.

What does "SATA 6Gb/s" and "SATA 3Gb/s" mean? Is it total bandwidth, so with 6 SATA ports – working at the same time – I would get 500 MB/s? It's still far off my typical 70+MB/s.

I know the quality of my hard-drive is an issue, it's a plain 3.5 non-SSD, and I know file size and file number make a difference, but is it supposed to get close to 500 MB/s?

Best Answer

  • Sata 6Gbs means the connection can theoretically transfer 6 GigaBits per second BEFORE encoding. This is a pure connection speed and has nothing to do with the capabilities of the device connected.

    So on a 6Gb/s link that would be (6,000,000,000 bits/8 bits per byte)*(8/10 link encoding) = 600 MegaBytes per second.

    Sata 3Gb/s ends up being 300 MB/s using the same formula.

    When you get 70+ MB/s "speed" you are seeing your device is maxing out at 70Mb/s capability and transferring that information over a SATA link capable of 600MB/s.