0TS2511 Sandisk Ultrastar DC SN655 30.72TB Gen4 NVMe PCI-E SSD

Architected for the Demands of the Modern Data Center

The Ultrastar DC SN655 series is built upon a foundation of deep industry insight and cutting-edge technology. It represents a strategic evolution in storage, moving beyond the limitations of SATA and SAS to embrace the low-latency, high-bandwidth future promised by NVMe over PCIe. This drive is meticulously crafted to address the core challenges faced by data center operators: maximizing performance per watt, optimizing total cost of ownership (TCO), and ensuring data integrity across petabytes of written data.

Core Technology and Interface: The PCIe Gen4 x4 NVMe Advantage

At the heart of the Ultrastar DC SN655's performance is its adoption of the PCI Express 4.0 x4 lane interface and the NVMe 1.4b protocol. This powerful combination is a significant leap over previous generations.

Doubling the Bandwidth of PCIe Gen3

PCIe 4.0 effectively doubles the data transfer rate per lane compared to PCIe 3.0, delivering up to 64 Gb/s of bi-directional bandwidth in a x4 configuration. This massive pipe allows the SN655 to saturate the interface with sequential read and write speeds that can exceed 7,000 MB/s, drastically reducing data access times and accelerating application responsiveness.

The U.3 Form Factor: Universal Flexibility for Diverse Infrastructures

The drive utilizes the U.3 15mm form factor, a key enabler for its deployment versatility. U.3 is a tri-mode interface that supports NVMe, SATA, and SAS protocols through a single, standardized connector. This allows data center managers to seamlessly integrate the high-performance SN655 into existing backplanes designed for any of these three protocols, future-proofing their investments and simplifying upgrades without requiring costly infrastructure overhauls. The 15mm z-height provides the necessary physical space to pack the dense 30.72TB of NAND flash, making it an ideal solution for high-density storage servers.

In-Depth Technical Specifications and Performance Analysis

To truly appreciate the capabilities of the SanDisk 0TS2511, one must delve into its detailed specifications and understand what they mean for real-world applications.

Massive Capacity: The 30.72TB Powerhouse

The headline feature of this specific model is its staggering 30.72 Terabytes of storage capacity. This level of density is a game-changer for data center economics.

Maximizing Rack-Space Efficiency

By consolidating what would previously require multiple lower-capacity drives into a single unit, the SN655 30.72TB dramatically increases the storage capacity per U of rack space. This leads to significant savings in power, cooling, and physical real estate, directly lowering the Total Cost of Ownership (TCO). It is perfectly suited for capacity-optimized storage servers, big data analytics repositories, and large-scale archival systems where data footprint is a primary concern.

3D TLC NAND: The Balance of Performance and Endurance

This capacity is achieved using high-density, enterprise-grade 3D TLC (Tri-Level Cell) NAND flash memory. While QLC NAND offers even higher densities, TLC provides a superior balance of write performance, latency, and endurance, which is essential for mixed-use and write-intensive workloads common in enterprise settings.

Blistering Performance Metrics

The SanDisk Ultrastar DC SN655 is engineered for speed, delivering performance that can eliminate storage bottlenecks.

Sequential Read and Write Speeds

With sequential read speeds of up to 7,000 MB/s and sequential write speeds of up to 3,800 MB/s, the drive can handle large file transfers, video streaming workloads, and data backup/restoration processes with remarkable efficiency.

Random I/O Performance (IOPS)

For transactional workloads like databases and virtualized environments, random I/O performance is paramount. The SN655 delivers impressive random read performance of up to 1,400,000 IOPS and random write performance of up to 260,000 IOPS at a queue depth of 16. This ensures that applications can process a massive number of small, simultaneous read and write requests with minimal delay.

Exceptional Endurance and Reliability

Enterprise drives are defined not just by their speed, but by their ability to perform consistently under constant, heavy use.

Drive Writes Per Day (DWPD) and Terabytes Written (TBW)

The 30.72TB model is rated for a 1.0 Drive Writes Per Day (DWPD) endurance over its 5-year warranty period. This means you can completely write the entire 30.72TB capacity once every day for five years. In absolute terms, this translates to a staggering 56,124 Terabytes Written (TBW). This level of endurance categorizes it as a mixed-use drive, capable of handling a balanced combination of read and write operations, making it incredibly versatile for a wide array of data center applications.

Mean Time Between Failures (MTBF) and Warranty

SanDisk backs the Ultrastar DC SN655 with a 2.5 million hour MTBF rating and a robust 5-year limited warranty. These figures are a testament to the drive's design integrity, component quality, and rigorous testing, providing peace of mind for mission-critical deployments.

Advanced Features for Enterprise-Grade Security

Beyond raw performance, the Ultrastar DC SN655 is packed with features that address the critical needs of security, data protection, and manageability in a complex data center environment.

TCG Enterprise Security with SED (Self-Encrypting Drive) Capabilities

Data security is non-negotiable. This drive complies with the TCG (Trusted Computing Group) Enterprise security specification.

Always-On, Hardware-Based AES 256-Bit Encryption

The SN655 functions as a Self-Encrypting Drive (SED), featuring always-on, hardware-based AES 256-bit encryption. This means all data written to the NAND is encrypted in real-time without any performance penalty. It protects data at rest from physical theft or unauthorized removal of drives from the chassis.

Secure Erase and Crypto Erase

When it's time to decommission or repurpose the drive, the TCG management interface allows for instantaneous Cryptographic Erase (Crypto Erase). Instead of overwriting every bit of data, which is time-consuming for a 30.72TB drive, Crypto Erase simply renders the old encryption key useless and generates a new one. The data becomes permanently inaccessible instantly, enhancing security and operational efficiency.

Power Loss Protection (PLP) and Data Integrity

Unexpected power loss is a primary cause of data corruption in storage systems. The Ultrastar DC SN655 is engineered to prevent this.

Robust Power Loss Capacitors

The drive incorporates an advanced Power Loss Protection (PLP) circuit. This system includes onboard capacitors that, in the event of a sudden power failure, provide enough reserved energy to complete any pending writes in the volatile DRAM cache and flush them to the non-volatile NAND flash. This ensures data consistency and prevents corruption, guaranteeing that committed writes are never lost.

Comprehensive Telemetry

Proactive health monitoring is key to preventing downtime. The SN655 supports NVMe Management Interface (NVMe-MI).

SMART Attributes and Vendor Unique Logs

Through NVMe-MI and standard SMART (Self-Monitoring, Analysis, and Reporting Technology) attributes, the drive provides detailed insights into its health, temperature, wear indicators, and remaining life. This allows system administrators to predict failures, plan maintenance, and replace drives proactively, ensuring maximum system uptime and reliability.

Ideal Workloads and Deployment Scenarios

The unique combination of high capacity, high performance, and robust endurance makes the SanDisk 0TS2511 Ultrastar DC SN655 30.72TB drive exceptionally well-suited for specific, demanding use cases.

Big Data and Analytics Platforms

Platforms like Hadoop, Splunk, and Elasticsearch that process and analyze massive datasets benefit immensely from the SN655's high sequential throughput and massive capacity, enabling faster data ingestion, query processing, and insight generation.

AI, ML, and Deep Learning Training

Training complex neural networks involves reading enormous training datasets and frequently writing model checkpoints. The low latency and high random read performance of the SN655 accelerate data loading, while its high endurance handles the constant write cycles, reducing model training times.

High-Performance Databases (OLTP & OLAP)

For Online Transaction Processing (OLTP) and Online Analytical Processing (OLAP) databases, storage I/O is often the bottleneck. The drive's high IOPS and consistent low latency ensure that database transactions and complex queries are executed with speed and reliability, supporting a greater number of concurrent users.

Cloud Storage and Hyper-Scale Infrastructure

In multi-tenant cloud environments and hyper-scale data centers, the drive's high density lowers TCO, its QoS features ensure performance isolation between tenants, and its security features protect customer data, making it an ideal building block for modern cloud storage stacks.

Media and Entertainment Workflows

For 4K/8K video editing, rendering, and content delivery networks (CDNs), the SN655's high sequential read/write speeds facilitate smooth playback of high-bitrate media and fast transfer of large video files, streamlining the entire production and distribution pipeline.