Western Digital WD40EFRX WD Red NAS Hard Drive - Hard drive - 4 TB - internal - 3.5 inch - SATA 6Gb/s - buffer: 64 MB - for WD My Cloud EX2, EX4

WD Red™ for Personal or Home Office
Stream, backup, share and organize your digital content at home with a NAS and WD Red™ drives designed to effortlessly share content with the devices in your personal or home office environments. NASware 3.0 technology increases your drives’ compatibility with your existing network and devices, TV, stereo, and more. Live in a connected world.

Exclusive NASware 3.0
Not just any drive will do. Get up to 48TB of capacity in your 8-bay system and with WD’s exclusive NASware 3.0 technology, you can optimize each and every drive. Built into every WD Red™ hard drive, NASware 3.0’s advanced technology improves your system’s storage performance by increasing compatibility, integration, upgradeability, and reliability.

Built for Optimum NAS Compatibility
Designed for personal and home office NAS systems, our unique algorithm balances performance and reliability in NAS and RAID environments. WD Red™ drives are optimized for environments where idle time is available to perform necessary background operations. To ensure optimal performance, always check compatibility with your system. WD Red™ drives may not be suitable for higher workload environments. For ZFS file systems and overall NAS system compatibility, we highly recommend WD Red™ Plus drives, which are optimized for higher workloads.¹

24/7 Environment 
Since your NAS system is always on, a reliable drive is essential. With an MTBF of up to 1 million hours, the WD Red™ drive is engineered to tackle 24x7 environments. 

Premium Support and a 3-year Limited Warranty
Confidently upgrade your NAS performance with the assurance of a 3-year limited warranty, coupled with world-class support services included with every WD Red™ drive. 

Desktop Drives vs. WD Red™
Do right by your NAS and choose the drive purpose-built for NAS with an array of features to help preserve your data and maintain optimum performance. Take the following into consideration when choosing a hard drive for your NAS:  

• Compatibility: Unlike desktop drives, these drives are tested for compatibility and optimum performance.  
• Reliability: The always-on environment of a NAS or RAID is a hot one, and desktop drives aren’t typically designed and tested under those conditions like WD Red™ is. 
• Error recovery controls: WD Red™ NAS hard drives are specifically designed with RAID error recovery control to help reduce failures within the NAS system. 
• Noise and Vibration Protection: Designed to operate solo, desktop drives typically offer little or no protection from the noise and vibration present in a multi-drive system. WD Red™ drives are designed to thrive in multi-bay NAS system environments.