Hii I got 2 external multimedia hard drive of toshiba one of them is 1TB and the other is 1.5TB... but when I connect both of them together 2 my laptop it shows only one of them at a time in My Computer... when I connect them individually it works fine... can anyone tell me how do I make them visible together so that I can back up my HDD... I even tried going in the administrator properties of disc management it shows both the drives in it but one of them which I connect second is deactivated and it doesn't allows me any option when I click on it... thnx you in advance...

What OS are you using? Have you told the system to "activate" the hard drive after it has been installed? Are these USB or ESATA connected HD's?

Hii it's a windows 7 64 bit and I can see the option of activation but its not highlighted I can't click on it... and both the HDD are USB ones...

Make sure they aren't trying to use the same drive letter.
DO a search for computer management and check.
You might need to assign a diffferent letter to one of them.

Hiii thanks for the reply... well I got it exchanged one of the 1.5 tb hdd with the seller and finally it did start working straight away with a new one so I guess it could be some manufacturing defect or something... finall got it sorted thanks a lot for your help appreciate it...