1. The main differences between SAS SSD and SATA SSD:
01 Differences in interface forms
SAS (Serial Attached SCSI) is Serial Attached SCSI, the same as SATA (Serial ATA), using serial technology to obtain higher transmission speeds. SAS has 2 pairs of transceiver channels, while SATA has only 1 pair of transceiver channels. The interface technology of SAS is backward compatible with SATA, but SATA is not backward compatible with the SAS interface. The SAS interface is designed to improve the performance, usability and expandability of the storage system, and to provide compatibility with SATA hard disks.
At the physical layer, the SAS interface and the SATA interface are fully compatible. In terms of interface standards, SATA is a sub-standard of SAS. As shown in the figure below, the SAS interface has an extra set of pins compared to SATA, which also reflects the two Differences in protocol.
02 Differences in protocol
SAS evolved from the SCSI protocol for enterprise-level applications and is oriented to enterprise-level scenario applications; while SATA evolved from the ATA protocol for consumer-level applications, and its design and implementation are relatively simple. Let's look at the differences between SATA and SAS from the comparison of the protocol layer, and the advantages of SAS:
03 Differences in performance
Because the protocol interface speed of SAS is much higher than that of SATA. SAS is a complete two-way system, while SATA inherits the characteristics of IDE and is a semi-two-way communication system. Therefore, the throughput of a SAS system can be twice that of a SATA system. The read and write performance of SATA SSD is generally around 500MB/s, while the performance of SAS SSD can reach 1GB/s, and the performance of SAS SSD with dual ports can reach 2GB/s. In terms of 4KB data random write performance, SAS also has more advantages than SATA:
04 Differences in reliability
SATA SSD applications are mostly in the consumer market, while applications in the enterprise level are mainly focused on small capacity (such as 480G, 960G) as server boot disks; while SAS SSD supports dual ports, which can meet the needs of enterprise-level high-reliability applications. As a data disk, SAS has more advantages in reliability , and SAS is also better than SATA in scenarios where enterprise-level requirements for data retention are high.
05 Application Differences
Although SAS and SATA are somewhat similar and can be replaced or complementary in some scenarios, SATA hard drives are more suitable for computers or some short-term storage. They can cope with scenarios where business performance and reliability are not high, and are more suitable for use in some small businesses. Application in internal storage.
SAS hard drives have more advantages in the enterprise field because their main requirements are high data throughput, low latency, and high reliability. They mainly cover enterprise-level server applications. Compared with SATA hard drives, they have higher read and write bandwidth and dual-mode storage. ports, high reliability and other features.
In addition, SAS hard drives also have higher performance and better data reliability: In terms of scalability, SAS can use expander hardware to achieve flexible storage topologies and can be mixed; the reliability advantage can be achieved by using SAS dual ports to build reliable system and eliminate any single point of failure, ensuring that the business process and data security will not be affected even in the case of a port outlet failure.
summary
Through the above five points, we can understand that the difference between SAS hard drives and SATA hard drives is not only an interface. The deep-seated reason is that SAS hard drives can meet high-performance, high-reliability enterprise-level applications, while SATA hard drives can only Meet non-business-critical applications.
2. In what scenarios can SAS SSD replace SATA SSD?
Let's first look at the usage scenarios of SSDs in servers:
As shown in the figure, we can find that in scenarios such as CPU direct connection to SSD, SAS or SATA SSD can be used as long as the Chipset supports the SAS protocol. If the Chipset only supports the SATA protocol, only SATA SSD can be used in this scenario. Another scenario is to expand and connect SSDs through HBA/Raid cards, then SAS, SATA, and NVMe can all be used. The above two scenarios mainly depend on the performance and cost requirements of the business.
In scenarios where SAS can be used instead of SATA, the advantages of SAS can provide more business benefits for enterprise-level scenarios:
1. Performance benefit: SAS SSD interface rate is 12Gb (SATA interface rate is 6Gb), with higher performance (performance doubled);
2. Higher reliability and better compatibility: SAS has better data reliability, the SAS protocol is more mature and complete, and the lower failure rate can also reduce maintenance costs;
3. Capacity and customer cost benefits: SAS SSD has a larger single disk capacity. Under the same total customer capacity and performance requirements, fewer hard disks are used. At the same time, server deployment can be reduced, which can not only reduce the customer's CAPEX budget, but also Help customers save computer room space and electricity bills, and reduce customer OPEX operating costs.
The replacement trend of SAS to SATA
Through the above analysis, we can clearly see that the advantages of SAS compared to SATA are: 1. Higher performance; 2. Better compatibility; 3. Higher reliability. And in which scenarios SAS can replace SATA and create more value for enterprise customers in terms of performance and data reliability.
Judging from the current market development, the SATA interface is decaying rapidly, the SAS market share is stable, and PCIe SSD is growing rapidly due to its higher bandwidth advantage and will gradually replace SATA as the mainstream trend.
SAS alternative to SATA
So what are the options for SAS SSD?
Because the technical difficulty of SAS is higher than that of SATA SSD, currently only Yilian can provide SAS SSD products and solutions among domestic storage manufacturers. With product performance and higher cost performance that surpass international manufacturers, Yilian SAS SSD has already It has been successfully used in core businesses in banking, finance and other industries that have high requirements for reliability. As the demand for domestically produced storage components continues to rise, more and more domestic enterprise-level SATA customers choose Yilian SAS SSD to replace the original SATA SSD. Yilian SAS SSD is a great storage tool that helps customers improve application performance and reduce TCO.
The following table shows the performance comparison between Yilian SAS SSD and SATA SSD from internationally renowned manufacturer A.
