WD Red™ Pro NAS Hard Drive 3D Active Balance Plus - Our enhanced dual-plane balance control technology significantly improves the overall drive performance and reliability. Hard drives that are not properly balanced may cause excessive vibration and noise in a multi-drive system, reduce the hard drive life span, and degrade the performance over time. Error Recovery Prevention - Built specifically for RAID and NAS environments, WD Red™ Pro drives come equipped with error recovery controls as part of NASware™ 3.0 technology to help reduce drive fallout in RAID applications. Extended Drive Testing - A NAS environment that has up to 24 bays is very demanding on a hard drive with added vibration and heat. This is why every WD Red™ Pro drive is shipped with extended thermal cycle burn-in testing to help ensure each drive is tested for extended reliable operation. 5-Year Limited-warranty - As an industry-leading hard drive manufacturer, Western Digital stands behind WD Red™ Pro drives for NAS with a 5-year limited warranty. Boost Your NAS - WD Red™ drives are available in capacities up to 22TB1 utilizing the OptiNAND™ technology’s capacity-enabling feature. Helps Protect Your Data - The innovative ArmorCache™ feature (22TB only) offers power loss protection of your data in write-cache enabled (WCE) mode while increasing performance in write-cache disabled mode. TECHNICAL SPECIFICATIONS Product Specifications Model number WD221KFGX Interface SATA 6 Gb/s Formatted capacity 22TB Form factor 3.5-inch Advanced Format (AF) Yes Recording Technology CMR RoHS compliant Yes Native Command queuing Yes OptiNAND™ technology Yes Performance Interface transfer rate (max) Interface speed 6 Gb/s Interface transfer rate 265 MB/s Cache (MB) 512 MB RPM 7200 Reliability/Data Integrity Load/unload cycles 600 000 MTBF (hours) 1 000 000 Limited warranty (years) 5 years Physical Dimensions Height (max) (in / mm) 1.028 / 26.1 Length (max) (in / mm) 5.787 / 147 Width (± .01 in.) (in / mm) 4 / 101.6 Weight (± 3% ) (lb / kg) 1.48 / 0.67 .