WD RE4 250 GB Enterprise Hard Drive: 3.5 Inch, 7200 RPM, SATA II, 64 MB Cache - WD2503ABYX Ideal for servers, video surveillance, and other demanding write-intensive applications, WD RE4 7200 RPM Enterprise SATA hard drives offer capacities up to 2 TB, 64 MB cache, and 4th generation vibration tolerance. Dual processor - With double the processing power, WD RE4 boasts the highest performance of any drive in the WD RE family. Thermal extended burn-in test - Each drive is put through extended burn-in testing with thermal cycling to ensure reliable operation. RAID-specific, time-limited error recovery (TLER) - Prevents drive fallout caused by the extended hard drive error-recovery processes common to desktop drives.