laptop challenge with USB disks

Hi folks
using a small powered 7-USB hub I wonder how many self powered USB passport disks you can attach still getting reasonable response and all functioning properly

I've got here 3 X 4 TB drives plus 1X 5 TB drive attached via the hub to a smallish HP envy laptop with i5 gen 6 processor and they are all working fine -- OK Host is Linux these drives are XFS formatted and I need to share them with Windows (Via SAMBA) so that's why they are on a Linux laptop. All these drives are "self powered" i.e no separate power other than standard usb cable connection. Hub is powered.

Just wonder at what point does the Disk I/O bus on the laptop get overwhelmed by these USB drives. There's no mega fast activity on them - some file sharing and streaming which isn't the most taxing tasks for HDD -- but just interested to see what numbers others have on external USB devices. Disks are /DV0, DV1, DV3, DV4 while an external 232 GB SSD is attached via a computers USB port so not included in the USB Hub attached count.



Cheers
jimbo

Are the "passport" drives actually the Western Digital My Passport or a different brand? Most 2.5" drive need only 5V power. The WD My Passport drives I have are all USB port powered, single cable and USB 3 which has more power available than USB 2. I have a couple of 2.5" cases that are USB 2 but require a Y-cable, one leg for data and power and the other leg for additional power, depends upon the requirement of the drive itself where some may be rated at 1A or less and others at higher. The larger 3.5" drives or cases require self-power as both 5V and 12V is required.

This reminds me of once I was asked to disassemble a man's office and attempt to do some cable management and tagging. I found probably 8 or 10 powered usb hubs daisy chained together across multiple desks with multiples of every usb device known to man, some of them powered, some using usb power. All I could do was stare open-mouthed at the customer and ask "WHY???"
His answer.."Well, I have them and never know when I'm going to need one of them."
I asked "Are they all working?"
"Most of the time."
My final answer. "I wouldn't touch this with a 10 foot pole." I wish I'd taken a picture but I was in too much a hurry to leave..