Cloud Block Storage is a highly available, highly reliable, low-cost, and customizable network block device that can be used as a standalone and expandable disk for CVMs. It provides data storage at the data block level and uses a three-copy distributed mechanism to ensure data reliability. Cloud Block Storage provides three types of cloud disks, SSD Cloud Storage, Premium Cloud Storage and HDD Cloud Storage. Disk performance, features and pricing vary for all three types. You can select the type you need according to the requirements of your deployed applications.

• SSD Cloud Storage: SSD cloud disks are based on NVMe SSD storage, and use a three-copy distributed mechanism to provide high-performance storage with low latency, high random IOPS, high throughput I/O capability, and data security up to 99.9999999%. SSD cloud disks are suitable for scenarios with high requirements for I/O performance.
• Premium Cloud Storage: Premium Coud Storage by Tencent Cloud is a hybrid storage type. It provides a high-performance storage capability that approaches SSD, and uses a three-copy distributed mechanism to ensure data reliability. Premium Cloud Storage is suitable for mid and small-sized applications with high requirements for data reliability and standard requirements for performance, as well as for mid and small-sized relational database applications such as MySQL, SQL Server, and PostgreSQL.
• HDD Cloud Storage: HDD cloud disks are the first generation of cloud disks provided by Tencent Cloud. It is suitable for business scenarios with low I/O loads where data is not accessed frequently. It uses magnetic storage, and a three-copy distributed mechanism to implement highly reliable data storage.

Performance differences between SSD cloud storage, Premium cloud storage, and HDD cloud storage are as follows:

The main difference between SSD Cloud Storage and Premium Cloud Storage is the I/O requirement.

SSD Cloud Storage is more suitable for intensive I/O scenarios, such as:

• High performance and high data reliability: suitable for high-load, mission-critical business systems. Provide three-copy data redundancy, and comprehensive capabilities for data backup, snapshots, and data restoration within seconds.
• Mid and large-sized databases: support mid and large-sized relational database applications that contain tables with millions of rows, such as MySQL, Oracle, SQL Server, and MongoDB.
• Large-sized NoSQL: satisfy storage performance requirements of NoSQL businesses such as HBase and Cassandra.
• Core business systems: suitable for I/O-intensive applications and other core business systems with high requirements for data reliability.
• Big data analysis: suitable for data analysis, data mining, business intelligence, and other fields. Provide distributed processing capabilities for data at TB and PB levels.

Premium Cloud Storage is suitable for the following data scenarios:

• Suitable for mid and small-sized databases and web servers. Provide long-term and stable I/O performance.
• Suitable for scenarios with balanced requirements for storage capacity and performance, such as enterprise office services and log services.
• Satisfy I/O requirements for core business testing and developing joint testing environments.

Pricing of the three types of cloud disks varies with region. Generally, high-performance SSD Cloud Storage is the most expensive. For pricing details, see Price Overview.