Question about drive transfer speeds

Energize · 11 May 2006 at 18:59

Ive seen sata 2 drives referred to as 3Gbps or 300MBps.

This cant be right though.

3,000,000,000 bits /8 = 375,000,000 bytes

375,000,000 bytes /1024 = 366210.9375 KB

366,201.9375 Kb /1024 = 357.62786865234375 MB

So one of the numbers is wrong, unless im missing something, the drives have to be either 300MBps or 3Gbps.

Unless the 300MBps refers to the inner zone and the 3Gbps the outer zone?

aardvark · 11 May 2006 at 19:21

the sata2 controller has a max speed of 300mb/s, however there ar no drives that get anywhere near that speed - my brand new seagate 250gb have an average speed of ~60mb/s, although the burst speed was ~200mb/s so i wouldn't worry about it.

Energize · 11 May 2006 at 19:41

I know but I just cant believe there would be such a blatent mistake in simple division.

aardvark · 11 May 2006 at 20:13

well, i've never seen sata2 referred to as anything other than 300mb/s.

i'm pretty sure its that.

Energize · 11 May 2006 at 20:23

http://forums.overclockers.co.uk/showthread.php?t=17504457

Its in the sticky that it is called 3Gbps.

Cyanide · 11 May 2006 at 20:54

Energize said:
Its in the sticky that it is called 3Gbps.

3Gbps = 3 GigaBITS per second

3GBps = 3 GigaBYTES per second

1 Byte is 8 bits, so 3Gbps is just about equal to 300MBps

It's all about the capital B :confused:

I think I'm right anyways... 'twas worth a try if I'm not

NightmareXX · 11 May 2006 at 21:36

Yea you got it there. Same with internet speeds.

For all those internet n0-0bs, they see a 1Mbps connection and go "Wow a 1 meg connection!". When in fact its max download speed is 120KB/s

Energize · 11 May 2006 at 22:03

Yes I know and 3Gbps = 357MBps I showed you the maths in my first post.

Cyanide · 11 May 2006 at 22:16

Energize said:
Yes I know and 3Gbps = 357MBps I showed you the maths in my first post.

I know... I was just saying that it's down to the b/B. As they're similar numbers the b is often used to make it seem bigger/faster/better than it really is, as pointed out by Nightmare about internet speeds.

There's nothing wrong with your figures, companies just tend to round numbers to their favour so that 300MBps = 3Gbps exactly, not 375MBps = 3Gbps.

Energize · 11 May 2006 at 22:20

Them saying the interface is only 300MBps though is not in their favour.

NightmareXX · 11 May 2006 at 23:10

True but if SATA was 150Mbps and SATA II suddenly jumped to 375Mbps don't you think someone'd think there was something strange going on?

Energize · 12 May 2006 at 01:19

No, why does there have to be a 100% speed increase? Maybe it is 300MBps but then it wouldnt be 3Gbps. Either way its either 300 or 357.

Dutch Guy · 12 May 2006 at 14:32

3Gbps = 300MB/s
SATA (and PCI-e) are async serial protocols with 2 bit per Byte overhead, so there are 10 bits per Byte

Energize · 12 May 2006 at 16:05

10 bits per byte = 286.1 MB, still not right. Unless they mean 300MiB and not MB, in which case they are wrong

.

Dutch Guy · 12 May 2006 at 18:04

3 gigabits per second = 300 megabytes per second

Energize · 12 May 2006 at 21:31

Dutch Guy said:
3 gigabits per second = 300 megabytes per second

It doesnt, it does equal 300 mebibytes though.

8 bits in a byte and it = 357megabytes

3,000,000,000 bits /8 = 375,000,000 bytes

375,000,000 bytes /1024 = 366210.9375 KB

366,201.9375 Kb /1024 = 357.62786865234375 MB

10 bits in a byte it = 286megabytes

3,000,000,000 bits /10 = 300,000,000 bytes

300,000,000 bytes /1024 = 292968.57 Kilobytes

292968.57 KB /1024 = 286.1 Megabytes