0F29561 WD Ultrastar DC HC520 12TB SAS 256 MB 3.5" Server HDD

High-Capacity 3.5in Nearline SAS Enterprise HDD featuring 4Kn CMR architecture with the 0F29561

The 0F29561 is a datacenter-class 12TB 3.5in nearline SAS HDD engineered for capacity-forward server and storage-array tiers where predictable sequential throughput and sustained availability are mandatory. Its 7200 RPM design with 256MB cache supports steady streaming workloads while maintaining consistent latency characteristics typical of enterprise HDD pools in rack-dense environments.

Architecturally, the 0F29561 combines a SAS interface with 4Kn native sector format to optimize modern storage stacks that prefer aligned I/O, reduced write amplification, and cleaner metadata handling at scale. Conventional Magnetic Recording (CMR) is selected for deterministic behavior under rebuild and heavy write conditions, while a helium-filled platform improves mechanical efficiency for multi-drive enclosures. For security-sensitive deployments, the 0F29561 includes Self-Encrypting Drive (SED) hardware encryption to support controlled data-at-rest protection without host CPU overhead. This design aligns well with capacity expansion in nearline tiers, where PCIe lanes and flash are reserved for performance layers and HDDs deliver economical bulk capacity with enterprise reliability targets.

Why Choose the 0F29561?

The 0F29561 provides a strong density-to-performance balance for SAS backplanes, enabling straightforward scaling of large nearline pools with predictable behavior under 24x7 duty cycles. The 0F29561 fits standard 3.5in service models, supports high-availability storage architectures, and is suitable for fleet deployment where consistency, manageability, and long-life operational profiles are required.

WD engineers Ultrastar platforms for continuous operation, tight vibration tolerance in multi-bay chassis, and compatibility with modern data centre qualification standards. With enterprise-focused reliability design targets, the 0F29561 supports disciplined lifecycle management across servers, JBODs, and storage arrays.

Key Applications:

• Nearline SAS capacity expansion
• Backup and restore repositories
• Archive and compliance retention
• Content and media libraries
• Object storage and cold tiers

At Happyware - Server Hardware you benefit from non-binding offers tailored to your storage architecture and procurement requirements, and can secure a bulk order discount when standardising the 0F29561 across racks or multi-site deployments.