Internal Hard drive ATA-100 for desktop Computer 250gb 7500rpm for MAC & PC from Western Digital, with WD RE WD2500SB. Rotational Speed 7200 rpm, Access Time 8.9 ms, Type of Drive Internal,Average Latency 4.2 ms Additional Features Fluid Dynamic Bearing (FDB) motor, Data Lifeguard Life in a desktop computer doesn't compare to the extreme environment in an always-on, high duty cycle RAID system. What's needed is a drive engineered to thrive in a high-intensity RAID system while still offering traditional low cost-per-capacity desktop value. That drive is the WD RE. Designed and manufactured to enterprise-class standards, WD RE drives provide enhanced reliability in a 24x7, continuous duty cycle environment.