TS500GSJ25M2 Transcend external HDD 2.5" 500GB USB. Use for FTP, DLNA and Samba downloads. Constantly warm and round without stopping Router Asus RT-N66U,firmware stock. Scares me a little that he constantly works and spins the disk.
On the contrary, as far as I know - the main load is at startup and stop. Personally, I have an old Seagate 320 gig spinning from 2008 year (with a few stops at service/moving) and die, like, still not going. Of the dangers - such is spinning hard to drop, and he will fulfill his 5 years and then will be deducted for retirement (most likely by the time he will be quite irrelevant in view of the final coming of the era of SSD)
It should not scare you, on the contrary - in this mode there will be problems with the Parking of the heads I recommend to look for a drain smartclt, or watch from a computer
Optimal HDD operating temperature of 35-40 degrees, a maximum of 65 degrees, after which the probability of failure increases. So it will be warm anyway. And spin the disk - the purpose of it is.
I have an external disk is not caught by the router, and to the media player - it network is filled with all sorts of things, so he also works constantly (idle). Warm, but for the past three years - no problems.
3years worked external Seagate, have always been connected and would not budge and do not shut off after a time ceased to appear, inside the hard, terrible crunch, gave in with a/C, after diagnosis, I was told that "You blew it" and you cannot recover the data, I was puzzled.