Depending on how you use your Chromebook, an external Hard Disk Drive should not really be necessary. Please have a look at this page first instead:-
It’s certainly a good idea not to burden the SSD of a Chromebook or Chromebox with lots of files. If you download music, video, PDF files etc. it’s better to remove them and store them elsewhere.
This is where you might think an external hard disk drive would come in handy. But my suggested route would be to routinely save downloaded files to a USB memory thumb drive and then transfer them to another computer (if you have one). Once there, the files could be backed up to an external hard disk drive as part of a normal backup routine. By doing things this way, your precious files are not only stored elsewhere but backed up too.
If you don’t have another computer, and just want somewhere to move downloaded files to from your Chromebook, the answer may be to buy a USB external hard disk drive. The only problem here is that the files would only be stored in one location with no backup. Always better to have a backup in case something goes wrong… especially so with anything that’s irreplaceable. Maybe I’m being a bit paranoid about this, but hard disks do occasionally fail – it’s happened to me twice.
So if you don’t have another computer and want a handy size external hard disk for your Chromebook, the best thing to do would be to buy as reliable a make as possible.
I’ve looked into this and the general consensus on the web is that the most reliable brand to go for is Western Digital. I came across quite a few tales of woe about Seagate drives for instance, so that’s probably one to avoid.
Reliability is probably the first priority for everyone but after that, perhaps one with a 500GB or 1TB capacity would be good. Other factors to consider include compact size, cost and maybe even style and colour. Another thing to bear in mind is that it would be better to have an external hard disk drive that does not need an external power source (or a second USB port for power as some do).
After looking around on the net, one that seems to fit the bill well is:-
It ticks all the boxes above, is USB 3.0/USB2.0 compliant and even comes in a choice of black, blue, red, silver or white.