I'm looking for a usb external hard drive Most Compatible with my Asus Router. One that will spin down when idle and can last for a long time time without getting unplugged.
First question, how many gigabytes of storage do you want?
Related to the first question, note that you can considerably simplify your life by simply using a USB 3.0 flash drive. Have a client who has been using a Patriot Supersonic Magnum 64 gig USB 3.0 flash drive for
two years now, plugged into an RT-AC66u, as their main file server for 4 users, 3 Windows and 1 Linux. That setup let the client discard an old Linux desktop server that he had been running for years. Never had the slightest problem with this setup, which used Merlin firmware from day 1. Did format the USB drive under Linux, in the ext2 format.
Pleasant thing about solid state drives plugged into the low-performance router USB ports, is that you at least get the full advantage of the super quick random access time. This shows as quick loading of small files into, for example, database and word processor programs. So with small kinds of random access, response time is nice even if the router bulk transfer rates are not high.
Here's a $48 dollar 128 gigabyte USB 3.0 drive:
http://www.newegg.com/Product/Product.aspx?Item=N82E16820220888
here's a 256 gigabyte USB 3.0 flash drive
http://www.newegg.com/Product/Product.aspx?Item=N82E16820178725
here's a 480 gig SSD solid state drive that you of course can put into a $20 dollar USB enclosure to give yourself an "inexpensive" 480gb USB drive:
http://www.newegg.com/Product/Product.aspx?Item=N82E16820178742