I’m currently watching the progress of a 4tB rsync file transfer, and i’m curious why the speeds are less than the theoretical read/write maximum speeds of the drives involved with the transfer. I know there’s a lot that can effect transfer speeds, so I guess i’m not asking why my transfer itself isn’t going faster. I’m more just curious what the bottlenecks could be typically?
Assuming a file transfer between 2 physical drives, and:
- Both drives are internal SATA III drives with
5.0GB/s5.0Gb/s read/write210Mb/s (this was the mistake: I was reading the sata III protocol speed as the disk speed) - files are being transferred using a simple rsync command
- there are no other processes running
What would be the likely bottlenecks? Could the motherboard/processor likely limit the speed? The available memory? Or the file structure of the files themselves (whether they are fragmented on the volumes or not)?
You didn’t mention if this is a HDD or an SDD. If it’s a HDD, you will never even reach SATA 2 speeds, although you should be able to saturate SATA 1. Realistically you might be able to push around 200MB/s on newer HDDs but that’s assuming nothing else gets in your way.