Cubase and external drives

Season’s greetings all.
I currently have all my samples, Kontakt and Cubase files sitting on an external Seagate hard drive but I’ve had problems of late saving work in progress files to the drive. It’s possible that it is the hard drive going into ‘hibernation’ when not being used. I use Caffeine on my iMac to keep it on. Is there an app that will keep the Seagate open in the same way?
I’m also posting on the Apple and Seagate support but I was wondering if anybody here has a solution?
Thanks in advance,
Screen Shot 2014-12-26 at 11.59.38.png