Hi, everyone, welcome to the fifth chapter in our Tencent Cloud practitioner course, introduction to Tencent Cloud Storage Products. At the end of this chapter, you will have a better understanding of the basics and types of storage technology, the features, principles and advantages of Tencent Cloud storage products and the billing plans of Tencent Cloud storage products. In this chapter, we'll cover four sections: Cloud storage basics, Tencent Cloud storage products, Tencent Cloud storage services and Cloud storage billing plans. This video will cover the first section, Cloud storage basics. Subsequent videos will cover the remaining three sections. Let's get started with Section 1, Cloud storage basics. In this video will cover the brief history of storage technology, different storage types, different storage media, storage tiering, Cloud storage versus traditional storage, and Tencent Cloud storage services. Before the advent of Cloud storage technology, people used to store data through direct attached storage or storing data locally in one data center and attaching storage into the storage fabric. As technology began to evolve, however, people started to store data through the storage area network, which allowed people to attach specific storage servers to the switch so that the servers could access any part of the network. Then came the distributed storage Server SAN, which integrated local discs scattered across a server into a unified storage resource pool through the distributed storage layer. Today, people use software-defined storage, which allows people to define the type and amount of Cloud storage they need through program APIs, providing increased flexibility. There are three main storage types: block storage, file storage, and object storage. It is important to understand the different strengths and weaknesses of each storage type and when to use a certain storage type over another storage type. Block storage is used to install the operating system and store data locally by caching to the operating system. Its advantages are low costs, fast transmission speeds and high read and write efficiency. Its disadvantages are required hardware investment, limited data sharing and no cross-system sharing. File storage is used to attach files into your own operating system and attach multiple operating systems. Its advantages are low costs and convenient file sharing, while its disadvantages are low read and write speeds and slow transmission speeds. Enabled by Cloud computing technologies, object storage is used to store data at the object level instead of at the file level or at the block level. It provides high-speed direct access to the disks of SAN, the distributed sharing of NAS and unlimited storage space. Tencent Cloud provides one type of storage media, solid state disks. Solid state disks are different from hard disk drives in that for HDDs the disk rotates and the head reads and writes data. While for SSDs, the master reads and writes concurrently using logical block addressing LBA, which means that there are no moving physical parts involved. SSDs have higher read and write speeds than HDDs, while HDDs have a higher maximum capacity than SDDs. Because HDDs are driven by a high power motor, they feature high power consumption and generate noise and heat. In contrast, because SSDs do not have a motor, they feature low power consumption, a standby feature, low noise and no heat. The presence of a physical motor also makes HDDs more vulnerable to shocks and failures than SSDs. Due to its faster speeds and higher stability, SSDs are more expensive than HDDs. Storage tiering is used to determine the type of storage device on which data should be stored based on its access frequency, performance requirements, and cost considerations. Data can be automatically migrated among the three different storage tiers; standard storage, cold storage, and archive storage. Standard storage includes Cloud block storage, Cloud file storage, and Cloud object storage. While cold storage includes infrequent access storage and archive storage includes cloud archives storage. What exactly are the differences between the three types of storage tiers? Standard storage, like its name sounds, is for the regular storage of data. Cold storage on the other hand, is for storing data that is infrequently accessed. For example, a few days after a news article is published online, the news article data is accessed significantly less frequently because everyone has heard about the news already, making it cold. Archive storage is for storing data offline for archival purposes. While all three storage types have high data persistence, standard storage has a 99.95 percent service availability, while cold storage and archive storage feature a 99.99 percent service availability. Standard storage and cold storage feature a millisecond level response time, while archive storage has a longer response time because customers must apply for data recovery in advance. Standard storage has no minimum billing time, while cold storage has a minimum billing time of 30 days and archive storage has a minimum billing time of 90 days. Regarding storage costs, standard storage has standard storage costs, while cold storage has low storage costs, and archive storage has very low storage costs. Standard storage does not involve any data retrieval fees, while cold storage involves low data retrieval fees, and archive storage involves high data retrieval fees. Finally, standard storage and archive storage involve very low read and write request fees, while cold storage involves low read and write request fees. Providing high availability, high performance and high throughput, standard storage is for hot data that is accessed at high frequencies and speeds. It is suitable for popular videos, social media photos, mobile apps, game apps, and dynamic websites. Providing high reliability and cost effectiveness, cold storage is for cold data that is accessed less frequently. It is suitable for Cloud storage, big data analysis, government and business data, and monitoring data. Lastly, providing high capacity at low cost, archive storage is for large amounts of data that are rarely accessed. It is suitable for medical imaging, scientific data and audio and video assets. Cloud storage differs from traditional storage in several aspects. In terms of functional requirements, Cloud storage provides online storage services for various network types, while traditional storage is for high performance computing, transaction processing, and other applications. Regarding capacity expansion, Cloud storage features unlimited capacity, elastic scaling, and linear performance. While traditional storage has limited maximum capacity is difficult to expand and has high costs. In terms of performance requirements, for Cloud storage the control system is isolated from the data system. The throughput is affected by network conditions, the bandwidth is theoretically unlimited, multiple storage nodes provide concurrent access, and load balancing is provided for hot data. However, for traditional storage, concurrent read and write is limited by the performance of a single device. Lastly, regarding data sharing, for Cloud storage the cluster file system supports flexible data sharing and centralized management. While for a traditional storage, the aggregated sharing of capacity and bandwidth among multiple devices is not supported. Cloud storage outperforms traditional storage in all aspects, from performance and security to reliability and cost effectiveness. Tencent Cloud offers Cloud storage products such as Cloud block storage, Cloud file storage, Cloud object storage and Cloud archive storage. Tencent Cloud also offers Cloud storage services such as Cloud storage gateway, Cloud data migration, and Cloud log service.