Using external USB hard drives via a USB hub connected to a MacBook Air

If I want to connect 2 usb external hard drives at the same time, will I be able to use a USB hub? I read somewhere "Never connect your external HD thru an external USB hub!"

Is this really true?

There is no 100% rule that applies in all situations.

For example:

• there are portable USB hard drives that do not require their own power source
• there are portable USB hard drives that do not require their own power source with some computers, but do with others
• there are USB hard drives that do require their own power source no matter the computer
• some USB hubs are powered hubs, while others are not
• some USB ports deliver more power than others

My recommendation

If you wish to connect external hard drives via a USB hub, especially is you're going to connect two of them simultaneously, then you should invest in a powered USB hub. By a powered USB hub I mean one that has its own power source. This way you're not relying on the MacBook Air to power the USB hub and two external hard drives simultaneously.