hard drives: firewire400 vs USB2 vs SATA150

[FudgeNuggets]

Correct me if I'm wrong but doesn't SATA150 offer much greater data transfer rates and less latency for a hard drive than does USB2 or Firewire400?

 

[Snugglebear]

SATA150 runs at 1.5 Gb/s and has less transport overhead than do the others. However, the cables can't run as far and aren't powered. This is fine for the internal use it was meant for, but not so good for external devices. USB2 is capable of a theoretical 480 Mb/s and again, is meant for a wide variety of devices hosted outside the machine. Firewire is about the same, capable of 400 Mb/s, longer cable lengths, and is meant for external devices. USB2 and Firewire also require tunneling of the disk commands, and combined with the platform overhead (i.e. drivers) involved the latency is also higher than using straight SATA.

 

[FudgeNuggets]

That's what I though. Thanks.
I was trying to decide whether to replace the 5400rpm drive in the mini with a 7200rpm drive or to put the 7200rpm in an USB2/Firewire400 enclosure and boot to it from there. It looks like internal is the way to go.

 

[Snugglebear]

Unless you have an overriding reason to buy an external drive, stick with internal. If you still want portability, consider a second drive as an external data drive, as that's their niche.

 

[Kurz]

SATA150 runs at
150MB you mean....
300MB for the SATA2 drives.

What he is right about is they do have lower lat.

 

[Snugglebear]

SATA150 runs at
150MB you mean....
300MB for the SATA2 drives.

What he is right about is they do have lower lat.

No, I really do mean that SATA150 runs at 1.5 Gb/s, as that is what the SATA-IO group specification calls for. Likewise, SATA300 uses 3.0 Gb/s signaling on the phyical layer which is to SATA-IO spec. There are two issues here:
1) The names of the SATA specs are not SATA150 & SATA300, as they are also not SATA-I & SATA-II. They are, properly, SATA 1.5Gbs & SATA 3Gbs.
2) SATA uses 8b/10b encoding, so each byte, while containing 8 bits of data, is encoded on the physical layer using 10 bits. Thus 1.5 Gb/s = 150 MB/s, thus the confusion over the names.

 

[FudgeNuggets]

I'll probably try to ebay the 5400rpm drive and if it doesn't sell or fetch enough then I'll toss it into an enclosure.

 

[PsycoPhreak]

If you do happen to opt for an external enclosure for extra storage, go with firewire, as it's sustained data transfer rate is greater than USB2.0. Don't fall prey to the hype about theoretical "burst" rates being faster with usb2.0. I have both and the "burst" rates have no effect, the firewire enclosure beats the usb2.0 hands down in real world, every day performance/data transfer.

 

[FudgeNuggets]

If you do happen to opt for an external enclosure for extra storage, go with firewire, as it's sustained data transfer rate is greater than USB2.0. Don't fall prey to the hype about theoretical "burst" rates being faster with usb2.0. I have both and the "burst" rates have no effect, the firewire enclosure beats the usb2.0 hands down in real world, every day performance/data transfer.

I noticed that to be true with the iPod and my video camera as well. It synchs with the iPod probably 5x-10x faster via Firewire.

 

[Snugglebear]

But only if you have a firewire port, which not every machine has. I agree, firewire is the better daily driver, but then only two of my 6 live machines have it. At least most external cases come with both interfaces.

 

[FudgeNuggets]

Well my PC has a firewire card and the MAC mini has it onboard.

 

[uOpt]

Another disadvantage of running over USB/FW is that all the monitoring (temperature, error rate etc.) stuff doesn't work over it.

I noticed that to be true with the iPod and my video camera as well. It synchs with the iPod probably 5x-10x faster via Firewire.

No, that is something different.

You run USB-1 for some reason. Either one of your deives doesn't do USB-2 (e.g. the fancy generation of ibooks did not) or your drives are messed up.