SCSI (SAS) technology has long been known for its high performance, reliability, and scalability amid the rapid development of data center storage technology. While solid-state drives (SSDs) are moving to PCIe physical interfaces using the NVMe protocol, SAS technology is not out of the past. On the contrary, with the introduction of the 24G+ SAS standard, SAS technology is taking its breath of life. The release of this new standard not only demonstrates the value of SAS technology for the broader data storage space, but also provides a new perspective on the future of hyperscale data centers.
The introduction of the 24G+ SAS standard and what it means
The introduction of five key new features to the 24G+ SAS standard maintains the original 2.4 GB/s speed, allowing SAS technology to remain competitive and valuable in the data storage space. The new standard, launched by the SNIA SCSI Trade Association Forum (STA) in collaboration with the INCITS/SCSI standards organization, marks a new direction for the future development of SAS technology.
Figure: The future of the 24G+ SAS standard in hyperscale data centers
Key features of 24G+ SAS and their impact
1. Command Duration Limit (CDL): This feature optimizes efficiency and reliability in large data environments by precisely controlling the latency of the hard disk drive (HDD) to ensure that operations can be completed within a specified timeframe. This is especially important for applications that require high reliability and low latency.
2. Format Presets: Simplifies the management process for CMR (Traditional Magnetic Recording) and SMR (Shingled Magnetic Recording) HDDs, helping to reduce the number of SKUs in the data center and reduce operating costs. This feature has a significant impact on the operational efficiency and cost control of data centers.
3. Logical Cleanup: Designed to identify and remove "bad disks" in datasets in hyperscale applications, improving the overall health and stability of the data center. This is essential for maintaining the long-term stable operation of the data center.
4. Rebuild Assistance: Helps identify and indicate unreadable partitions that need to be rebuilt from other sources, enhancing SSD resiliency and reliability in complex data environments. This feature is important for improving data availability and reducing the risk of data loss.
5. Persistent Connectivity: By keeping connections open to optimize performance, high-performance SSDs reduce the wear and tear associated with repeatedly switching connections on and off, further improving SSD endurance and efficiency. This has a positive effect on improving the energy efficiency of data centers and reducing maintenance costs.
SAS vs. NVMe
While the NVMe protocol is popular for its high performance and low latency, SAS technology still has its own unique advantages in certain use cases. The NVMe protocol is designed from the ground up to take full advantage of the low latency and parallelism of PCIe SSDs, as well as the parallelism of modern processors, platforms, and applications. However, SAS technology offers advantages in terms of reliability, scalability, and compatibility with legacy systems. SAS interfaces have been around in data centers for more than 30 years, delivering high performance, reliability and scalability for data centers.
SAS technology offers some unique advantages over NVMe in improving data center storage efficiency:
1. Compatibility: The SAS interface is backwards compatible with the SATA standard, which means that the backplane of the SAS system can be connected to both SAS and SATA drives. This compatibility provides data centers with greater flexibility to choose different storage solutions based on demand and cost-effectiveness.
2. Scalability: SAS technology is scalable, with up to 16,384 disk devices connected. This scalability provides powerful scale-out capabilities for storage systems in data centers, helping to meet large-scale data storage and processing needs.
3. Full-duplex operation: SAS APIs support full-duplex data operations, that is, data can be read and written at the same time, improving data throughput efficiency. This is critical for data centers that require high throughput and real-time data processing.
4. Maturity and stability: SAS technology has matured and stabilized over the years, which is an important consideration for data centers looking for reliability. In contrast, despite NVMe's speed advantages, SAS may be preferred for stability and reliability in some use cases.
5. Simplified internal connectivity design: SAS technology helps simplify internal connectivity design and reduce design costs while improving the server's cooling and ventilation capabilities. This has a positive impact on data center operations and long-term cost control.
6. Continued technical support and innovation: SAS technology has received continued technical support and innovation due to its long-standing market position, such as the introduction of the 24G+ SAS standard, which shows that SAS technology is still evolving to adapt to new storage needs.
The future of SAS storage
"24G+ SAS is a big step forward for our industry and continues to demonstrate the value of SAS technology in the broader data storage space," said Cameron T. Brett, Chairman of the Board of Directors of the SNIA STA Forum. This view not only affirms the position of SAS technology in the current market, but also indicates its potential for future growth.
Summary
The release of the 24G+ SAS standard is not only an affirmation of SAS technology, but also an expectation for its future development. As data centers continue to demand storage performance and efficiency, 24G+ SAS technology will provide more powerful and flexible storage solutions for both traditional servers and hyperscale data centers. Despite the advantages of NVMe technology in some aspects, SAS technology has proven that it still has irreplaceable value and potential in the field of data storage through continuous innovation and improvement. With the promotion and application of the 24G+ SAS standard, SAS technology is expected to play a greater role in hyperscale data centers and promote the development and progress of data center storage technology.
