0B47078 Western Digital Ultrastar DC HA340 8TB 7.2K RPM SATA-6Gbps HDD

High-Capacity Enterprise Hard Drive Overview

The Western Digital 0B47078 Ultrastar DC HA340 8TB internal hard disk drive is built for reliable, high-performance data storage in enterprise and data center environments. Designed with advanced technology and durable components, this HDD delivers consistent speed, large capacity, and long-term dependability.

General Product Details

Manufacturer & Model Information

• Brand: Western Digital
• Model Number: 0B47078
• Product Category: Internal Hard Disk Drive
• Product Line: Ultrastar
• Series: DC HA340

Technical Specifications

Storage & Interface

• Total Capacity: 8TB enterprise-grade storage
• Drive Type: Internal HDD
• Interface: SATA III (6Gb/s)
• Form Factor: 3.5-inch

Reliability & Endurance

• MTBF: Up to 2 million hours for enhanced reliability
• Sector Format: 512e for broad system compatibility

Performance Characteristics

Speed & Data Transfer

• Rotational Speed: 7200 RPM for fast data access
• Maximum Interface Speed: 6 Gb/s
• Sustained Transfer Rate: Up to 267 MB/s

Latency & Cache

• Average Latency: 4.16 ms
• Cache Buffer: 256MB for smoother performance

Physical Dimensions

Size & Build

• Z-Height: 26.1 mm
• Dimensions (W x D): 101.6 x 147 mm
• Weight: Approximately 715 g

Core Architecture & Technology Breakdown

The Western Digital 0B47078 Ultrastar DC HA340’s performance and reliability are not accidental; they are the result of deliberate architectural choices and cutting-edge technologies implemented by Western Digital.

HelioSeal Technology: The Foundation of Capacity and Efficiency

A defining feature of the HA340 platform is its use of HelioSeal technology. By filling the drive with helium—a gas less dense and with lower viscosity than air—Western Digital achieves multiple critical advantages:

Increased Areal Density: Reduced turbulence allows platters to be placed closer together, enabling more platters and heads in a standard 3.5-inch form factor, directly enabling the 8TB capacity.
Reduced Power Consumption: The drive motors expend significantly less energy overcoming fluid drag, leading to lower operational costs, especially critical in large-scale deployments with thousands of drives.
Improved Thermal Performance: Helium conducts heat more efficiently than air, aiding in heat dissipation from critical components and contributing to overall drive stability and longevity.
Enhanced Reliability: The sealed environment is impervious to atmospheric contamination and corrosion, protecting the pristine HDA (Head Disk Assembly) over the drive's operational life.

Mechanical and Firmware Enhancements

Beyond helium, the HA340 incorporates a suite of mechanical and firmware features designed for 24/7/365 operation.

3D Active Balance Plus Technology

This dual-stage balance system ensures smooth operation at 7,200 RPM. A primary balance is achieved during manufacturing, while a secondary real-time balance correction system actively compensates for any minor shifts during operation or due to environmental factors. This minimizes vibration, a key contributor to drive failure in multi-drive systems, and ensures consistent performance.

StableTrac and Rotary Acceleration Feed Forward (RAFF)

The StableTrac technology secures the motor shaft at both ends, reducing system-induced vibration and stabilizing platters for more accurate tracking during read/write operations. Coupled with RAFF, which optimizes operation in vibration-prone multi-bay enclosures, these technologies ensure the drive can maintain performance and integrity even in the densely packed, high-vibration environment of a modern server or storage JBOD.

Triple-Stage Actuator (TSA) Technology

For precise head positioning, the HA340 utilizes a triple-stage actuator. It combines a conventional voice coil motor (VCO) with a microactuator on the arm and a piezoelectric nano-actuator on the slider itself. This allows for extremely fine, rapid adjustments to the head position, resulting in higher track density, improved read/write accuracy, and better performance handling fragmented data.

Performance Characteristics & Use Case Alignment

With a SATA 6Gb/s interface, 256MB cache, and 7,200 RPM speed, the DC HA340 8TB is optimized for sequential throughput. It consistently delivers high megabytes-per-second (MB/s) performance for large block data transfers, making it an ideal candidate for specific workloads.

Ideal Application Scenarios

Bulk Storage & Active Archives: Perfect for storing large, rarely deleted datasets like medical imaging, seismic data, video surveillance footage, and regulatory archives where access is periodic but performance is needed when called upon.
Content Delivery & Distribution: Serves as an excellent tier for CDN nodes, storing vast libraries of media files (videos, software ISOs, game assets) for fast, sequential delivery to end-users.
Scale-Out Storage & Object Storage Backends: Integrates seamlessly into hyperscale and private cloud object storage platforms (like Ceph or Swift deployments) as a cost-effective, high-density capacity tier.
Enterprise RAID Arrays & JBODs: Provides reliable, consistent performance in RAID 5, RAID 6, or RAID 10 configurations for general enterprise file serving, backup targets, and secondary storage pools.

Considerations for Mixed Workloads

While its sequential performance is strong, as a high-capacity HDD, its random I/O performance (IOPS) is inherently lower than SSDs or even lower-capacity, high-RPM drives. Therefore, it is less suited for transactional databases, virtualization hosts, or other latency-sensitive applications as a primary tier. Its value shines in throughput-centric, capacity-first roles.

Reliability and Workload Ratings

The Western Digital 0B47078 "DC" in Ultrastar DC stands for "Data Center," and this classification comes with rigorous specifications.

Unmatched Annualized Workload Rating

A standout specification for the Ultrastar DC HA340 is its 550TB/year workload rating. This is over 10 times the rating of a typical desktop hard drive (~55TB/year). This metric, defined by JEDEC, indicates the amount of data that can be written to and read from the drive annually over its warranty period. A 550TB/year rating translates to approximately 150-180GB of data transfer every single day, year-round. This makes it capable of handling heavy write-intensive periods common in data logging, data aggregation, and active archival applications.

Mean Time Between Failures (MTBF) and Error Rates

Western Digital rates the HA340 with a 2.5 million hour MTBF, an extraordinarily high figure that represents statistical reliability in large populations. It also boasts an unrecoverable read error rate (URE) of 1 sector in 10^15 bits read, which is the industry standard for enterprise-class drives. This low error rate is crucial in multi-drive RAID rebuilds, reducing the probability of a second error during a rebuild that could lead to array failure.

Compatibility, Integration & The SATA Advantage

The Western Digital 0B47078 choice of a SATA 6Gb/s interface over SAS in this model is strategic, offering distinct advantages for certain deployments.

Ubiquitous Connectivity

The SATA interface is universally supported on every server motherboard, HBA (Host Bus Adapter), and RAID controller. This simplifies procurement, integration, and spare parts stocking. There is no need for specialized, often more expensive, SAS controllers or expanders.

Cost-Effective Scaling

SATA infrastructure—from cables to controllers—is generally more affordable than its SAS counterpart. For deployments where the advanced features of dual-port SAS (critical for true high-availability) or higher queue depths are not required, SATA provides a perfectly performant and significantly more economical path to petabyte-scale storage.

512e Format for Seamless Deployment

The drive's use of 512e (512-byte emulation) sector formatting means it presents itself to the host system as using traditional 512-byte sectors, even though it physically uses larger 4K (4096-byte) sectors internally. This ensures compatibility with legacy operating systems, hypervisors, and applications that may not be fully "4K-native" or "Advanced Format" aware, eliminating a potential deployment hurdle.

Comparative Context: Where the HA340 8TB Fits in the Storage Hierarchy

Understanding the 0B47078 Ultrastar DC HA340 requires seeing its place in the broader storage ecosystem.

Vs. Consumer-Grade & NAS Drives

Unlike WD Red or WD Blue drives, the Ultrastar is built to entirely different specifications. Its components, firmware, and validation processes are designed for constant vibration, higher ambient temperatures, and relentless 24/7 operation. The 550TB/year workload rating dwarfs that of even prosumer NAS drives, which typically top out at 180TB/year.

Vs. Higher-RPM Enterprise SAS Drives

Compared to a 10K or 15K RPM SAS drive, the HA340 sacrifices some random I/O performance and latency for vastly superior capacity, power efficiency, and cost-per-GB. They serve different tiers: SAS for performance-primary, SATA for capacity-primary.

Vs. Solid State Drives (SSDs)

SSDs are unbeatable in latency, IOPS, and power efficiency for active data. However, for cold, warm, or bulk data where the cost-per-TB is the paramount concern, the HA340 offers a compelling, mature, and highly reliable alternative. A hybrid or tiered storage system often uses SSDs for hot data and drives like the HA340 for the larger capacity tier.

Within the Ultrastar Family

The HA340 represents the high-capacity, value-optimized SATA line within the Ultrastar family. It sits alongside Ultrastar SAS drives (like the HC550) for performance-density and NVMe SSDs (like the Ultrastar DC SN series) for ultra-low latency workloads, providing a complete portfolio for data center architects.