Backing Up Data On One Computer To Extra Hard Drive Space On Another Computer

Here is my setup:
Computer A - Main computer, Windows 10:
Partitioned into 2 drives (1 physical drive), both NTFS
Partition 1: OS
Partition 2: Data, except for some data that is used by programs (programs that want the data in specific directories)

Computer B - Backup computer Windows 8.1 computer:
Partition 1: OS
Partition 2: backup of data on computer A, partition 1 and partition 2.

So my question involves transferring that data. I suppose I can use ethernet but since the older computer is 10/100 ethernet, I was thinking that I could use Sata. Is there some kind of a sata splitter that you could use to be able to connect to a sata drive that's inside of the computer? For power to the drive, I would have computer B be running a Linux OS off of the USB or DVD drive. This is just a way to get power to the drive without using the drive at the same time. I think it wont use that drive unless computer B starts trying to use virtual ram on that drive. I don't think it will do that, though, because I think that's something that operating systems initiate, while they are running, and just on the drive that they are installed on.

Another option is to connect the 2 computers using a usb cord. But, I think computer B only has usb 2.0, so ethernet would be better and not cost anything.

 

I have never heard of a SATA "splitter". I don't think that would be a good idea anyway because of the way operating systems open and lock files when accessing them. If two OSs tried to access the same file at the same time - which would happen when copying from 1 drive to the other - I think it would corrupt the file tables and create the real potential for data loss.

Unless you physically remove the drive from one computer and attach it to the other, your best bet is still over your network. Note that 100Mbps is still likely much faster than your ISP provided Internet download speeds - unless you have fiber going to your home.

Another advantage to using Ethernet is you can locate the second computer in a remote part of the house. This provide a little extra "physical" security for you data in case there is a fire in your computer room, for example, both computers will not be lost.

Don't forget, inexpensive 10/100/1000Mbps PCIe Ethernet cards like this one can be had pretty cheap. Or you can add a 300Mbps wireless adapter cheaply too.

 

USB 2 theoretically is 480 Mbps - Ethernet is 10/ 100 Mbps or possibly 1 Gbps - still I have seen Ethernet transfer faster than USB, you just would need to test out your situation.
Assuming these are desktops you can add USB 3.0 or Gigabit Ethernet. If you want to pull the drive(s) get a "drive toaster" (usb drive bay/ drive dock) and use it.