sata-disks are generally not best suited for enterprise use, but if you want to stick with them, use at least some designed for 24/7 operation, sometimes marketed as "enterprise edition", or "raid edition". These have generally higher reliability, time-limited error recovery and a few other useful features. I have used seagate constellations and hitachi travelstars (2.5") with good results.
If possible stay away from various "green/blue" or "eco" editions. Those have very agressive power-saving routines (i.e. variable speed), frequently putting them to sleep/offline mode, and some controllers might represent this as drive being disconnected.
