How many usb portable hard drives can be connected to a PC at the same time?

[peter236]

Suppose the PC motherboard has a couple of usb ports.

How many usb portable hard drives can be connected to a PC at the same time? If I connect 2 external portable drives to 2 different usb ports, will that be okay? I presume one drive connected to each usb port should be alright. I would like to copy files from one drive to another.

 

[Soundmanred]

I've had 9 at one time, so 2 shouldn't be a problem.

 

[richaron]

127

 

[imagoon]

127 drives per usb host port. On some system boards one host port might provide 2-6 usb ports on the back of the system.

 

[boochi]

If they are powered over USB, you may only be able to run one or two.

 

[peter236]

My 2 external portable drives do not have their own power adapter. But I just connect them to different usb ports at the back of the PC. I am not using any usb hubs or any chaining at all.

 

[DesiPower]

If they are powered over USB, you may only be able to run one or two.

yeah, so how exactly does that work? is it dependent on the controller? like one controller can only supply 2A of current or something like that? does that capacity/amp depend on the controller type/make? or is it the number of port? each port can provide 1A....

 

[imagoon]

yeah, so how exactly does that work? is it dependent on the controller? like one controller can only supply 2A of current or something like that? does that capacity/amp depend on the controller type/make? or is it the number of port? each port can provide 1A....

Spec (1.0 / 2.0) provides .5A to each port. Depending on how the ports are divided up, you can have .5A at each or some smaller amount. Some older system boards used a root hub to make one controller give you 2-6 ports but with only .25A or .1A available. Others used more power to give you .5A at all ports. It is dependent on board design.

 

[Anteaus]

The practical limit is 26, unless you somehow hack windows to allow alphanumeric drive assignments. The physical limit is higher, but that will require swapping assignments as needed. However, you might be able to map drives to folders instead of drive letters.

OP, as long as they are self powered drives you won't have any problems. Also, multiple USB ports might belong to the same controller which mean shared bandwidth, so if you want to maximize transfer speeds make sure they are on seperate controllers. In the event you have only one USB 3.0 controller, it would be acceptable to use both drives on the one controller. .02