0F29560 Western Digital Ultrastar he12 12TB 7.2K RPM SAS-12GBPS 4kn 3.5 Inch HDD

Western Digital Ultrastar 12TB Enterprise HDD

The Western Digital Ultrastar DC HC520 (model 0F29560) represents a pinnacle of high-capacity enterprise storage engineering, designed specifically for demanding data center environments. This 12TB helium-sealed hard disk drive leverages proven host-managed Shingled Magnetic Recording (HM-SMR) technology alongside a high-performance SAS 12Gb/s interface to deliver exceptional storage density and reliability for bulk data storage applications, including object storage, secondary storage, and large-scale backup and archiving solutions.

High-Density Reliability

At the heart of the Ultrastar DC HC520's design is Western Digital's proprietary HelioSeal platform. This advanced manufacturing process hermetically seals the drive's internal components with helium, a gas that is significantly less dense than air. This foundational technology enables several critical performance and reliability benefits essential for 24/7 data center operation.

Reduced Drag and Power Efficiency

The low-density helium atmosphere inside the drive enclosure creates minimal resistance for the spinning platters and actuator arm. This drastic reduction in mechanical drag translates directly into lower power consumption, reducing the Total Cost of Ownership (TCO) for large-scale deployments. The drive requires less energy to maintain its 7,200 RPM operational speed, generating less heat and decreasing the burden on data center cooling systems.

Enhanced Operational Longevity

Helium is an inert gas, meaning it does not react with the internal components of the hard drive. This eliminates the risk of oxidation and corrosion on the platters and heads over the drive's operational lifetime, a significant factor in achieving the 2.5 million hours Mean Time Between Failures (MTBF) rating. The hermetic seal also prevents any microscopic contaminants from entering the HDA (Head Disk Assembly), ensuring long-term data integrity.

SAS 12Gb/s Interface: Enterprise-Grade Connectivity

The 0F29560 Ultrastar DC HC520 is equipped with a dual-port SAS (Serial Attached SCSI) 12Gb/s interface, the enterprise standard for high-performance, mission-critical storage. This interface provides distinct advantages over consumer-grade SATA connections in a server environment.

Full Duplex Dual-Port Capability

The 0F29560 SAS interface supports full-duplex communication, meaning data can be read from and written to the drive simultaneously. The dual-port design provides a redundant path to the drive. In a multi-host environment or a redundant storage array (like SAS Expanders), if one host or controller fails, the second port can maintain connectivity, ensuring high availability and eliminating single points of failure.

Enhanced Error Recovery and Command Queuing

SAS includes a more robust command set and error recovery protocol compared to SATA. This allows for better handling of command queuing (up to 256 commands with TCQ) and more sophisticated communication between the drive and the host bus adapter (HBA) or RAID controller. This results in more predictable latency and superior performance in heavy I/O workloads.

Backward Compatibility

The 0F29560 SAS 12Gb/s interface is fully backward compatible with previous-generation 6Gb/s and 3Gb/s SAS infrastructures. This allows for seamless integration into existing data center environments without requiring a complete infrastructure overhaul. The drive will automatically negotiate to the highest supported speed of the connected controller.

Predictable Performance in the Right Workload

When managed correctly by a compatible host system, Host-Managed SMR delivers highly predictable and efficient performance for large, sequential write workloads. It eliminates the performance variability and "write amplification" that can occur in Drive-Managed SMR drives, which try to hide the SMR complexity from the host, often leading to severe latency spikes during garbage collection processes.

Ideal Use Case Alignment

Host-Managed SMR is perfectly suited for applications where data is written once and read many times (WORM), or where data is appended sequentially. This makes the HC520 an excellent choice for large-scale object storage (like S3-compatible storage), video surveillance archives, scientific data repositories, and legal/compliance archives.

High Performance

While optimized for sequential throughput, the Ultrastar DC HC520 is engineered with robust components to deliver consistent performance within its designed workload parameters.

7,200 RPM Spindle Speed and Sustained Transfer Rates

The drive operates at a standard enterprise-class spindle speed of 7,200 RPM. Combined with the high areal density provided by SMR and HelioSeal, this enables high sustained sequential transfer rates, maximizing the throughput for large file operations and minimizing the time required for large-scale data ingestion and retrieval tasks.

256MB DDR3 Buffer

The drive is equipped with a 256MB DDR3 SDRAM cache. In a Host-Managed SMR drive, this buffer plays a critical role in optimizing write operations and improving read performance.

Write Caching and Sequencing

The large buffer allows the drive to accept bursty host write data quickly, acknowledging the write command once the data is safely in the volatile cache. The drive's firmware can then sequence and organize this data for the most efficient sequential write to the SMR zones on the media, smoothing out the write process.

Read Pre-Fetch and Caching

For read operations, the buffer is used to store frequently accessed data and to pre-fetch adjacent data sectors that the host is likely to request next. This significantly reduces read latency for sequential read patterns, which are common in the drive's target applications.

Advanced Format 4K Native Sector Technology (4Kn)

The Ultrastar DC HC520 utilizes 4K Native (4Kn) sector formatting, where the physical and logical sector size is 4096 bytes. This modern sector architecture offers several advantages over the legacy 512-byte sector format.

Increased Format Efficiency and ECC Strength

Larger sectors reduce the overhead required for gap, sync, and address mark areas between sectors on the physical platter. This space saving increases the effective format efficiency, allowing more user data to be stored. Furthermore, the larger sector size allows for a more powerful Error Correction Code (ECC), enabling the drive to detect and correct a greater number of potential errors, thus enhancing data integrity.