why isnt sata3 fully utilized even nowdays?

[bal723]

so i had this question for a long time, why isnt sata3 6gb/sec is never utilized anywhere and why do we even need 6gb/sec sata then?

even pcie 3.0 m2 nvme can reach up to 3600mb/s which is 3.6g/sec but still way faster than any sata drive to exist

[MarkPol88]

Are you sure you are not mistaking Gigabytes with Gigabits?

[Tan3l6]

3 minutes ago, bal723 said:

so i had this question for a long time, why isnt sata3 6gb/sec is never utilized anywhere and why do we even need 6gb/sec sata then?

even pcie 3.0 m2 nvme can reach up to 3600mb/s which is 3.6g/sec but still way faster than any sata drive to exist

SATA 3.0 is 6 Gigabits per second

PCIe 3.0 is reaching 3.6 Gigabytes per second

[bal723]

Just now, Tan3l6 said:

SATA 3.0 is 6 Gigabits per second

PCIe 3.0 is reaching 3.6 Gigabytes per second

ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh

[OhYou_]

full utilization is something like 760~ MB/s read OR right.
there is some overhead because the data itself is encapsulated by various bits and bytes to keep track of it on its way to and from the drive.
there is also almost always some of the bandwith being consumed in the opposite dirrection.
So in practice you never really see anything higher than 650ish MB/s

 

oh you mean other thing

[Dedayog]

6 minutes ago, bal723 said:

so i had this question for a long time, why isnt sata3 6gb/sec is never utilized anywhere and why do we even need 6gb/sec sata then?

even pcie 3.0 m2 nvme can reach up to 3600mb/s which is 3.6g/sec but still way faster than any sata drive to exist

You're confusing bandwidth vs speed.

 

 

[bal723]

sata got me confused xd

[tkitch]

halfway decent SATA SSDs easily cap SATA Speeds.

[mariushm]

SATA uses 8:10 encoding, meaning for every 8 bits of data, there's 2 bits used for error checking and correction and other things.
So out of those 6 gbps or 6000 mbps , the actual data that can be transmitted is 6000 / 10 * 8 = 600 * 8 = 4800 mbps or 600 MB/s

Because data is further arranged in packets with headers and footers, realistically the maximum throughput (actual data read from or written to a sata device ) will be around 570 MB/s.

Note that a sata controller may be limited by the connection to the system : for example a 2 port sata controller may be connected to the system through a single pci-e 3.0 lane, so while each sata port may do 550 MB+, in total the maximum connection to system will be less than around 950 MB/s. It works out if both sata ports are not used at maximum at same time.

As another example, inside the chipset, the 6 port sata controller part may be connected to the rest of the chipset internally using 4 pci-e 2.0 lanes - so you get a total of 2 GB/s shared between 6 sata ports each capable of 550 MB/s

M.2 uses pci-e lanes, each pci-e lane is capable of 250 MB / 500 MB / 985 MB / 1969 MB / 3938 MB (from pci-e 1.0 to pci-e 5.0)
Versions 1 and 2 uses 8:10 encoding, from version 3 128 : 130 encoding is used, hence the weirder values.