I'm setting up a 5Tb storage array using 6x Western Digital WD10EADS 1TB drives in RAID5.
Usage of this array during the day is intermittent. If I set them to spin down after an hour, they will spin up and down a few times a day. In addition, they will spin up once at night while automated backups are being performed.
Should I set these drives to spin down when not in use or leave them spinning? My main concern is reliability. Does the mechanical wear from spinning 24x7 exceed that of spinning up and down a few times a day, and what of the thermal stress from spinning up/down?
Power consumption is not an issue as they only consume 2.8w while spinning idle.
I'd love to hear from anyone that has some insight into failure rates related to the above usage scenarios.