Server storage SAS hard disk technology

                  The rapid development of the enterprise network has made the supporting servers and their accessories also innovated. Many new technologies are used to achieve better development of the enterprise network. For example, this kind of server-based storage technology will be introduced to you. ―SAS; The following will give you a general understanding of the technology and related products, and hope to bring this understanding to the actual purchase and use.

First, technical characteristics

SAS is the abbreviation of Serial Attached SCSI, namely serial connection SCSI, which is generated to solve the drawbacks of parallel technology. Simply put, this technology is a successor to parallel SCSI, which provides higher performance, scalability, and reliability for enterprise storage applications. In addition, the SAS interface is SATA-compatible, giving you the flexibility to integrate SAS or SATA devices into your system.

Initially, the data throughput of products using this type of technology can reach about 3Gbps, but with the further improvement of technology, the speed of subsequent generations will gradually increase to 12Gbps; and the full double of SAS technology The mode allows the device to transmit data in both directions at the same time, which effectively doubles the available bandwidth of the link. Some other features of this technology can be found in the following points:

Support for SAS and SATA devices, but with a thinner cable.

With a maximum access capacity of 128 devices, it provides maximum performance expansion for the entire system.

Provides fault tolerance through SAS expanders or dual-port SAS devices, and saves host space with a 2.5-inch hard drive.

Second, SAS hard disk products

The SAS-based hard disk was actually launched by many manufacturers in 2005, only due to the temporary impact of technology and market demand.

There are not many follow-up products from manufacturers. However, it is still possible to see its impressive performance from a small number of products.

Product Description: This drive has a design capability of 1.4 million hours of mean time between failure (MTTF) and a speed of 15,000 RPM; in addition it provides a maximum sustained data rate of 98 MB per second, and The average search time of 3.0 milliseconds. Also includes a 16 MB ECC protected cache.

Product Analysis: Maxtor is the first US manufacturer to officially ship a SAS hard drive, which is targeted primarily at high-end hardware players and enterprise users.

Product Description: The average seek time of 3.3 ms in this series, the mean latency period of 2 ms, the rotational speed of 15,000 rpm for the motor, built-in cache capacity of 16MB, which support up to the maximum 16,384 Connection; this series is available in 36GB, 73GB, 147GB three different capacity versions, respectively, using 2, 3, 5 glass discs, each with Ultra320SCSI and 2Gb/s FCAL (FibreChannel-ArbitratedLoop, Fibre Channel Arbitration Loop) Road) Models of the two interfaces.

Product Review: This is the only enterprise-class hard drive that uses Hitachi load/load technology in Hitachi. This technology minimizes the overall damage factor of the hard drive. It is used primarily in mission-critical computing environments, such as online business processing, high-intensity database queries, and other multi-user applications.

Product Description: This product capacity of 37GB (maximum capacity of 147GB), the specific model ST336754SS. Offering up to 15,000 RPM, the product has an internal 8MB data cache and an average search time of 3.5 milliseconds. This product is the fastest, lowest heat, lowest noise and most reliable in terms of performance and reliability. Enterprise hard drive.

Product Analysis: This product is Seagate's lowest performance hard disk, high performance and high reliability, is the mainstream enterprise hard disk product; it is also the industry's first mean time between failures (MTBF) A 1.4K hour 15K RPM hard drive that can be used in enterprise storage environments.

Product Description: This is Fujitsu's first hard drive with Serial Attached SCSI (SAS). The product has a speed of 10,000 rpm, a size of 2.5 inches, an average seek time of 4ms, a cache capacity of 8Mb, a theoretical SAS transmission speed of 3Gbps, and a power consumption of only 4.5W during operation; its initial product The capacity is 73Gb and 36Gb.

Product Analysis: This product combines the advantages of traditional SCSI and SATA, and breaks through the bottleneck of SCSI transmission speed and volume. Due to the 2.5-inch specification, the efficiency is unchanged but space is saved. Hold 10 such hard drives in a 1U server. Coupled with Fujitsu's more than 35 years of experience in magnetoresistive head technology, SAS drives are more performance-guaranteed; they can be used in high-end and mission-critical applications such as database servers, storage arrays, NAS and SUN systems.

S3 Adapter

This is the "bridge" between the SAS hard disk and the host. It is similar to the SCSI control chip, because now the motherboard is generally There is no integrated control chip that supports SAS, so an additional expansion card is required, similar to a SCSI controller card. Currently, such control cards are mainly provided by the well-known LSI Logic and Adaptec. The following is a brief description of one of them (LSI Logic SAS3442X SAS adapter), because generally speaking, SAS hard drives should be shipped with the corresponding SAS adapter.

Product Description: This product uses the common PCI-X interface of the server motherboard, which provides a SAS hard disk interface, and the data cable that is delivered provides four extended hard disk interfaces; It provides strong support for SAS hard drive connections and can connect up to 122 SAS expanders when used in a system. With 300 MB/s of bandwidth per port (full-duplex 600 MB/s) and an overall throughput of 2.4 GB/s (full-duplex 4.8 GB/s), it delivers unprecedented performance for workstations and servers.

Added: When you purchase a specific product, you have to remind everyone that although the backplane of the SAS system can be connected to a dual-port, high-performance SAS drive, it can also be connected to high capacity and low. The cost of the SATA drive; but the SATA system is not compatible with SAS, so the SAS drive cannot be connected to the SATA backplane.

Summary: In general, SAS technology delivers the high performance, scalability and reliability required for mainstream server and enterprise storage with higher bandwidth requirements; it can satisfy such things as online shopping and banking. Transactional data application environment for high-frequency and real-time, random data access environments; and physical and software compatible with SATA hard drives. Many excellent technical features make hard disk products based on such technologies in large-scale popularization in 2006; and it is foreseeable that with the reduction of cost and performance, SAS-based hard disks will replace traditional ones. High-speed SCSI hard drives become the mainstream of future enterprise storage systems or server hard drives.