You wrote TRANSFER. That means that if during the transfer if it corrupted content that all would be lost. You did not write you were going to COPY it over then decide what to do later.
Beyond that, yes I've left my externals on for days with an unit at the office that runs for months at a time between power downs. Was there a problem with these drives that caused you to worry about using them for a normal amount of time?
I have two external hard disks hooked on to the back of my PC. I think the port is USB 2.0.
I wish to transfer all data from one extrenal hard disk to the other. The thing is, the amount I am transferring is around 530 GB. It is virtually impossible for me to transfer it to my internal hard disk and then transfer to the new external.
I wanted to ask, will it be ok to connect both the extrenals and leave the transfer on overnight? I don't want any damage to happen to either of my external hard disks.