Learn from scratch SAS technology and SAS hard drive

Disk media in the storage area is the most critical device, and all data and information is stored on disk media. The reading speed of the data is determined by the connection interface of the disk media. We used to do data storage through SCSI or SATA interfaces and hard drives. But in recent years a new technology has increasingly been favored by small and medium-sized enterprises and even large enterprises. Is the SAS technology and its corresponding SAS hard drive. Today we have nothing to learn about the SAS technology and the advantages of using SAS drives.

First, common disk technology and interface types pros and Cons:

Networked storage devices can now be broadly grouped into three broad categories, high-end midrange and near-end (Near-line). High-end storage devices are mainly fiber channel, because the fiber channel transmission speed, so high-end storage fiber devices are mostly used in mission-critical data storage in large capacity. The midrange storage device is primarily a SCSI device, and has a long history of being used for mass storage of business-grade critical data. Near-end is the new storage area in recent years, its products are mainly serial ATA (Serial ATA, abbreviation is SATA), apply to the bulk storage of non-critical data, the purpose is to replace the data backup that used to use tape previously.

The biggest advantage of Fibre Channel storage devices is the speed of transmission, but his price is very high, maintenance is relatively troublesome, and SCSI device access speed is relatively fast, the price is in a moderate position, but his extensibility is slightly close, Each SCSI interface card can be connected to up to 15 (single channel) or 30 (dual-channel) devices. SATA is the rapid development of technology in recent years, his biggest advantage is that the price is cheap, and speed is not much slower than the SCSI interface, with the development of SATA data reading speed is approaching and catching up with the SCSI interface. In addition, because SATA's hard disk prices are getting lower and larger, the capacity is gradually available for data backup.

As a result, traditional enterprise-class storage, with SCSI hard drives and Fibre Channel as the primary storage platform for performance and stability, and ATA for non-critical data or desktop PCs, is changing as SATA technology rises and SATA devices mature. More and more people are beginning to pay attention to SATA this serial data storage connection mode.

Second, what is the SAS technology? (Figure 1)

Because of the rapid development of SATA technology and the advantages of many, it will allow more people to consider whether there is a way to combine SATA with SCSI, so that they can play both advantages. In this case, SAS emerged.

SAS is a new generation of SCSI technology, the same as today's popular serial ATA (SATA) hard drives, using serial technology to achieve higher transmission speed, and improve the internal space by shortening the link line. SAS is a new interface developed after the parallel SCSI interface. This interface is designed to improve the performance, availability, and scalability of the storage system, providing compatibility with serial ATA (Serial ATA, abbreviated SATA) hard drives.

SAS interface technology can be backward-compatible with SATA. The back panel (backplane) of the SAS system can connect both a dual-port, high-performance SAS Drive and a high-capacity, Low-cost SATA Drive. Because the port of the SAS drive looks similar to the port shape of the SATA drive, SAS drives and SATA drives can be present in a single storage system. However, it should be noted that the SATA system is not compatible with SAS, so SAS drives cannot be connected to the SATA backplane. Because of the compatibility of SAS system, IT staff can use the hard disk of different interfaces to meet the requirements of each kind of application in capacity or efficiency, so it has more flexibility to expand storage system, so as to maximize the investment benefit of storage equipment. To put it bluntly, the SAS interface technology is a SCSI hard drive using a serial interface, which is compatible with a SATA hard drive, and we can install a SAS hard drive or SATA drive on the SAS interface. (Figure 2)