Educate me please. (SSD)

hanrak

hanrak

hanrak

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Ok so if i have a SATA 2 motherboard i can transfer at 3GBs a sec yep? (hardware provided) So if i have a new motherboard capable of SATA 3 i can transfer at 6GBs. Ok what i want to know is that how could you ever reach that speed with some of the fasted SSD drives that only have a transfer rate of 500MBs?

Sorry for the silly question but im willing to learn!
 
Sorry if i come across as dumb and im sure i do but the fact SATA 2 says its 3GB a second implies it really does transfer at that speed and not at 300MB second. What am i missing here?!!
 
Im not entirely certain but its just like your internet, if you have 50mb your gonna max your download at 5.8mb/sec.

You may have to divide by 8 and that gives you your real performance statistic.
 
You need to understand SATA speeds and understand the difference between bits and bytes. :)


SATA 1

SATA 1 = 1.5 Gb/s (<this means 1.5 gigabits per second)

The actual real life uncoded transfer rate becomes 1.2 Gb/s. (Not many things reach their theoretical max speed, and reach close to it due to inefficiencies or overheads). Ok, so you take 1.2 Gb/s and you divide by 8 to give you the transfer rate in MB/s (megabytes per second (you use capital B for bytes and small B for bits)). You do this because there are 8 bits in a byte. Not sure how much this is teaching you to suck eggs? There are 8 bits in a byte because there just are. :)

So 1.2 Gb/s = 1200 mb/s (I mean 1.2 gigabits is the same as 1200 mega bits per second)

.... 1200 / 8 = 150 MB/s (150 megabytes per second)

Most mechanical Hard disk drives would not exceed this and therefore SATA 2 is rarely "required" unless running very fast drives or raid setups. Or....SSDs.



SATA 2

SATA 2 = 3 Gb/s = actual of 2.4 Gb/s = 2400 / 8 = 300 MB/s

So here you can see why SATA 2 is good for SSDs


SATA 3

SATA 3 = 6 Gb/s = actual 4.8 Gb/s = 4800 / 8 = 600 MB/s



So you can see already that even SATA 3 can be a bottleneck for very fast SSD drives running in Raid 0 configurations.
 
Thanks for the lesson guys, very interesting and explains a lot. I gotta be honest tho i remember the bits a bytes thing from years ago now. I find it a little backward tho. Why describe it in that sence when selling it? Why not just say sata 2 runs at max 300mb/s and the ssd/hardrive runs at its speed. Why say it like they do?
 
hanrak said:
Thanks for the lesson guys, very interesting and explains a lot. I gotta be honest tho i remember the bits a bytes thing from years ago now. I find it a little backward tho. Why describe it in that sence when selling it? Why not just say sata 2 runs at max 300mb/s and the ssd/hardrive runs at its speed. Why say it like they do?
Click to expand...

Bits is used for the bandwidth of all interfaces, is how it is and not every packet on communication interfaces is a whole byte.
 
Use capital and lowercase to avoid confusion. MB for megabytes, Gb for gigabits.

If you're being very thorough, windows etc. actually report in MiB and GiB (mebi- and gibi- respectively, which are 1024) not GB and MB which are 1000.
 
Ok, so if sata 2 is 300mb/s how come if you plug a Vertex 3 in for example, you won't get the full 300mb/s?

Noob here :p
 
SATA2 is 300 MB/s not 300 mb/s. Do you understand the difference? A Vertex 3 (according to google) has read speeds of 516 MB/s and writes of 493 MB/s which exceeds SATA2 and means that it would run at a max of 300 MB/s, aka SATA2 would bottleneck it.

A HDD/SSD is as fast as it is based on how it was made and how good it is. SATA is a type of bus to carry the data between the motherboard of the PC and the storage device (SSD/HDD) and these SATA buses have limits. I think this was explained above really. Are you still struggling with this? If so which bit?
 
JamesM said:
Ok, so if sata 2 is 300mb/s how come if you plug a Vertex 3 in for example, you won't get the full 300mb/s?

Noob here :p
Click to expand...

Theoretically you should get 300MB/s with a vertex 3 on SATA2, but in practice no transfer system ever works perfectly. The slightest error in signalling between the SATA controller and the hard drive or an incorrectable error in the data stream caused by interference means you will never max out at 300MB/S

This is the same for any data connection, whether SATA, ethernet or USB.
 
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