What are the implications of plugging a USB 2.0 hub into a USB 3.0 hub

Question

I have a notebook that when im at home i use for work with a keyboard/mouse, a monitor (the monitor is HDMI) and some peripheals.

Well, i already have a cheap USB 2.0 powered (5v/1A) hub with 7 ports, in this hub i plug my keyboard, my mouse, a printer and the nobreak sensors (the power supply is only needed for heavier devices such external hard drives, so, i dont use it because the only things that draw power from this hub are the keyboard and mice and the USB 2.0 port can handle that). All of that is plugged into a USB 2.0 port on my notebook (it has two 2.0 ports and one 3.0 port, i let the USB 3.0 port free because sometimes i use for my external hard drive, its a 500GB unpowered 2.5 USB 3.0 hard disk).

My idea is to add two fixed external hard drives that will stay on my desk and when i come home i will plug into my notebook and use it. I choose for two 2TB 3.5 powered USB 3.0 hard drives, so, i will buy a far less cheap USB 3.0 adapter, but, unfortunally, this adapter has only four ports and i cant connect all my stuff plus the two hard drives. I think that even splitting the USB 3.0 speed (that is high), it will still get the full speed of the hard drives (i think that the drives cant pass 160MBPs each).

The disks have their independent power supply, so, i will not suck all the power of the USB 3.0 port.

So, my idea is to plug my current USB 2.0 hub in one of the ports of the USB 3.0 hub and use two others to plug the hard drives and the last usb 3.0 port to eventually plug my portable hard drive (unpowered).

The good thing is that the power supply that comes with the usb 2.0 port hub also works with the usb 3.0 hub, and if i need extra juice (something that i think i dont, because the only things actually drawing power are the keyboard/mice and eventually the 2.5 hard disk) i can use it.

My question is, how my notebook USB 3.0 port will handle it? It will work nicelly? The USB 3.0 port will nivelate all devices to 2.0 because of the second hub? And what about the speed, the USB 3.0 port speed is capable of handling 2 hard drive + some minor peripheals?

I also can plug the 2.0 hub into another USB 2.0 port on my notebook but, its another cord to plug every time that a get home and is one less usb port free on my notebook.

USB 3.0 HUB: 2 Powered USB 3.0 Disk + 1 Unpowered USB 3.0 Disk + 1 USB 2.0 HUB

USB 2.0 HUB: Mice + Keyboard + Printer + Nobreak Sensor (all 2.0) + Rarelly some device such a pen drive.

The USB 3.0 hub will be connected to the USB 3.0 port on my notebook.

Solution 1

My PC is currently operating pretty much as you describe: there is a USB 3.0 hub plugged into the the PC's USB 3.0 port, and I've got a USB 2.0 hub plugged into the USB 3.0 hub. USB 3.0 devices such as external hard-disk drives operate at full speed plugged into the USB 3.0 hub (or other USB 3.0 ports of the PC) and USB 2.0 devices work at their limits in any port. There are powered USB 3.0 hubs with 7 to 10 ports for US$20-30 from Amazon, NewEgg and elsewhere that you might consider, too.

Hope this helps you.

Solution 2

USB is forwards and backwards compatible. The device and host will negotiate the greatest commonly supported link speed. If you are getting a message telling you to plug it into a USB 2.0 port you can safely ignore it.

Comments

[Ramhound]

You plug a USB 3.0 hub into a 2.0 port you have yourself a 2.0 hub. If that doesn't help clarify your question

[Will]

Potential Duplicate: superuser.com/questions/293189/…

[Ramhound]

@fixer1234 - Result is the same. You have a 2.0 HUB connected to a 3.0 port. If you connect to that hub those devices will be connected to a USB 2.0 hub.

[fixer1234]

You don't describe the interface on the hard drives (old external USB 2.0 drive or enclosure? SATA drive you will interface with a SATA/USB 3.0 adapter?). Real-world data rates: USB 3.0 is roughly equal to SATA, so one SATA hard drive will hog the bandwidth of the USB 3.0 connection.

[fixer1234]

@Ramhound - You're talking about the USB 2.0 not getting faster by plugging it into a USB 3.0 port, right? Not that plugging a USB 2.0 device or hub into a 3.0 hub makes the 3.0 hub act like a 2.0 hub on its other ports?

[Ramhound]

@fixer1234 - If he only has one 3.0 port and plugs a 2.0 hub into one of the free slots on the 3.0 hub, then any device plugged into the 2.0 hub would become a 2.0 device. Either way my comment was correct you end up with a 2.0 hub.

[h0m3]

@Ramhold - If i plug a USB 2.0 hub into another USB 3.0 hub, the other ports on the USB 3.0 hub will continue to be 3.0 speed or the USB interface will nivelate all to 2.0? I know that the ports on USB 2.0 hub will be limited to USB 2.0 speed.

[h0m3]

@fixer1234 - They are USB 3.0/SATA III Drives (powered). But the USB 3.0 Speed isn't 6GBit/s? I know that SATA III is half of that speed, but even the modern disks today hardly pass 1.4GBit/s... So i think that i can get the full speed of four drives plugged into a USB 3.0 port, or im not right?

[fixer1234]

You have the hubs and drives in hand. Why not run a test using collections of different sized files and varying numbers of drives connected through the 3.0 hub, and see what difference in completion times you get when you perform concurrent operations. Then post an answer here. That's worth some upvotes. Everything else is hypothetical discussion. Also, the bottom line is how satisfactory the performance is for you. If you need multiple HDDs connected and working concurrently, and that arrangement is your only practical option, you need to weigh any performance tradeoffs for yourself.

[Will]

In addendum, USB 3.0 plugs are just slightly larger than their 2.0 cousins. However, each of the males (2.0 & 3.0) can be plugged into each of the females (2.0 & 3.0). Earlier than USB 2.0 (1.1/1.0/etc) are too small and cannot fit a USB 3.0 connector. The USB standard actually stops you from shooting yourself in the foot