Western Digital 16TB SATA 6G 7.2K RPM LFF 3.5" 4Kn HDD Ultrastar DC HC550 WUH721816ALN604

Part Numbers: WUH721816ALN604, 0F38353, 0F38477

The Western Digital Ultrastar DC HC550 WUH721816ALN604 is a high-capacity enterprise-class hard drive engineered for hyperscale cloud infrastructure, enterprise servers, SAN environments, storage arrays, and high-performance NAS deployments. Built on Western Digital's advanced HelioSeal® helium platform, this 16TB hard drive delivers exceptional storage density, reliability, and power efficiency for 24/7 mission-critical workloads.

Featuring CMR (Conventional Magnetic Recording) technology, 7200 RPM performance, and a SATA 6Gb/s interface, the HC550 is designed to meet the demanding requirements of modern data centers and enterprise storage applications.

Key Features

• 16TB Enterprise Storage Capacity
• SATA III 6Gb/s Interface
• 7200 RPM Spindle Speed
• 3.5" Large Form Factor (LFF)
• 4Kn (4K Native) Sector Format
• HelioSeal® Helium-Filled Technology
• CMR (Conventional Magnetic Recording)
• Energy-Assisted Magnetic Recording (EAMR)
• 512MB Cache
• 24x7 Enterprise Operation
• 2.5 Million Hour MTBF
• 550TB Annual Workload Rating

Core Configuration

• Manufacturer: Western Digital
• Product Line: Ultrastar DC HC550
• Model Number: WUH721816ALN604
• Related Part Numbers: 0F38353, 0F38477
• Capacity: 16TB
• Form Factor: 3.5" LFF
• Interface: SATA III 6Gb/s
• Sector Format: 4Kn (4096-Byte Native)
• Recording Technology: CMR with EAMR
• Platform: 9-Disk Helium-Sealed Architecture

Performance

• Rotational Speed: 7200 RPM
• Cache: 512MB
• Sustained Transfer Rate: Up to 262 MB/s
• Average Latency: 4.16 ms
• Burst Transfer Rate: Up to 600 MB/s

Reliability

• MTBF: 2.5 Million Hours
• Annualized Failure Rate (AFR): 0.35%
• Workload Rating: 550TB Per Year
• Load/Unload Cycles: 600,000
• Enterprise-Class 24/7 Operation

Power Requirements

• Operating Power: 8.8W
• Idle Power: 5.6W
• Input Voltage: +5V / +12V
• Supports SATA Power Disable (PWDIS)

Physical Specifications

• Height: 26.1 mm
• Width: 101.6 mm
• Depth: 147 mm
• Weight: Approximately 690g (1.52 lbs)

Dell PowerEdge Servers

Compatible with most modern Dell PowerEdge servers using 3.5" drive bays, including:

• PowerEdge R740
• PowerEdge R750
• PowerEdge R760
• PowerEdge T550
• Other Gen14, Gen15, and Gen16 PowerEdge Platforms

May also be installed in some Gen13 systems such as the R730, although mounting may require using the front and rear screw positions due to the drive's enterprise chassis design.

Supermicro Servers

Compatible with most:

• Supermicro 3.5" Hot-Swap Trays
• Supermicro Storage Servers
• Supermicro Enterprise Chassis
• Supermicro JBOD Systems

The drive mounts directly into standard Supermicro metal and tool-less carriers.

RAID Controller Compatibility

Supported Controllers

• Dell PERC H730
• Dell PERC H740P
• Dell PERC H755
• Dell PERC H345
• Dell PERC H355
• Broadcom / LSI 9300 Series
• Broadcom / LSI 9400 Series
• Broadcom / LSI 9500 Series

Not Recommended for

• Dell PERC H310
• Dell PERC H710
• Dell PERC S140
• Dell PERC S150

Older RAID controllers may not properly recognize 4Kn enterprise drives.

Compatible with:

• Synology Enterprise RackStation Models
• QNAP Enterprise Rackmount NAS Systems
• TrueNAS Core
• TrueNAS Scale
• Unraid
• Proxmox
• VMware ESXi
• Enterprise Storage Arrays
• Software RAID and ZFS Deployments using supported HBAs

Not recommended for older consumer NAS devices or legacy storage systems that do not support 4Kn drives.

This Is NOT a Standard 512e Hard Drive

The WUH721816ALN604 ships as a 4Kn (4K Native) drive.

• Physical Sectors: 4096 Bytes
• Logical Sectors: 4096 Bytes
• No 512-byte emulation enabled by default

Because this is a 4Kn model, compatibility depends on support from your:

• Operating System
• RAID Controller
• HBA
• NAS Platform

Modern operating systems such as Windows Server 2012+, Windows 10/11, Linux, VMware ESXi, Proxmox, TrueNAS, and Unraid typically support 4Kn drives natively.

This drive supports SATA Pin 3 Power Disable technology.

Enterprise Servers

Works normally in:

• Dell PowerEdge Backplanes
• Supermicro Backplanes
• Enterprise Storage Enclosures
• Data Center Platforms

Desktop Systems

Some desktop power supplies provide 3.3V power on SATA Pin 3, which may prevent the drive from powering on.

If using this drive in a desktop environment, additional configuration such as a Molex-to-SATA adapter or Pin 3 isolation may be required.

• HelioSeal® 6th Generation Helium Platform
• Triple Stage Actuator (TSA)
• Rotational Vibration Safeguard (RVS)
• Media Cache Plus Technology
• Energy-Assisted Magnetic Recording (EAMR)
• Enterprise Vibration Protection
• High-Density Multi-Drive Environment Optimization

Please Verify Compatibility Before Purchase

Because this is a 4Kn enterprise hard drive, please verify that your server, RAID controller, NAS, or storage platform supports 4Kn (4K Native) drives before purchasing.

If you provide your server model, NAS model, or RAID controller information, we can help verify compatibility prior to shipment.