OSMC RPi3 on hard drive

I am running OSMC on RPi3. However something - I suspect PVR Simple client I am using for IPTV is killing SD cards every two months. I ruled out RPi3 board (I have one spare). It doesn’t matter if it is Samsung, Sandisk, Verbatim or no-name SD card. The only difference is speed.

Is it possible to install OSMC on hard drive sata/ssd? If not, is possible to buffer to RAM or external hard drive?

Yes,it’s called USB install. For the time being you would still need a SD Card for the boot partition but as nothing will be written to that card after you booted that should not be an issue.