SATAIII 600MB - is it for all drives or for each?

Question

Hard disks

Nubian question: If the motherboard has 4 SATAIII 6Gbps ports, is it for each port or for all disks?
I ask because I connected 4 disks to a PC and when copying from disk to disk I get 100-120MB / s
Motherboard on the B550 chipset, fresh. Proc Ryzen 1600. Well, that is, it's clearly not about PC performance.
Tried looking for an answer but couldn't find it.

Answer 1

Obviously, when copying from disk to disk, you will get something about the linear speed of the disk, which is about 120-150 megabytes sec
. More precisely, there will be a minimum of the speed of reading the first disk and writing to another.
Greater speed can be obtained if you combine disks in RAID-0

Answer 2

If the motherboard has 4 SATAIII 6Gbps ports - is it for each port or for all drives?

For each

I ask because I connected 4 disks to a PC and when copying from disk to disk I get 100-120MB / s

What about disks? Maybe this is normal for them.
When copying between two sata ssds, speeds above 400 megabytes per second are quite achievable.