Tencent Cloud Cloud Block Storage (CBS) provides a persistent block storage service for CVM instances. CBS automatically stores data in multiple redundant copies in an availability zone to eliminate the risk of single points of data failure, providing up to 99.9999999% data reliability. CBS offers cloud disks in multiple types and specifications to achieve stable and low-latency storage performance. CBS can be mounted to or unmounted from instances in the same availability zone, and its storage capacity can be altered in a few minutes, meeting elastic storage requirements. Payment is based on actual usage, and allowing you to enjoy all the above features at a low price point.

Elastic Scalability

One single cloud disk can store up to 16 TB of data, and up to 10 cloud disks (160 TB) can be mounted to one single CVM instance. The storage capacity can be freely configured and scaled as needed to meet the requirements of your business, enabling efficient processing of big data at the terabyte and petabyte levels.

Multiple Storage Types

CBS offers three volume options including HDD cloud disk, premium cloud disk and SSD cloud disk to meet different business storage requirements. SSD cloud disk uses NVMe high-performance SSD, and one single disk is capable of providing 24,000 random IOPS and a throughput of 260 MB/s, making it easy for your business to sustain high-throughput database access.

High Stability and Reliability

Before each storage write request is returned to the user, CBS ensures that the data has already been successfully written to three cross-rack storage nodes. The data replication mechanism of CBS is higher than the industry average, ensuring rapid data migration and recovery in case that any copy fails and achieving up to 99.9999999% data reliability to protect your applications from component failures.

Easy to Use

CBS can be used and managed through simple operations such as creation, mounting, unmounting and deletion, reducing the costs of manual management and deployment.

Snapshot Backup

Data can be backed up by taking point-in-time snapshots of cloud disks to prevent data loss due to tampering or accidental deletion and ensure quick rollbacks in the event of business failure.


A cloud disk can be freely mounted and unmounted in the same region without the need to shut down or restart the server. Its storage capacity can be configured elastically and scaled on demand. Up to 20 cloud disks can be mounted to one single virtual machine, providing up to 320 TB of storage that fully satisfies the requirements of high-volume file systems in various businesses such as big data, data warehousing and log processing.

Data Backup

A snapshot is a full copy of a cloud disk that includes an image of the disk at the point in time when the copy starts and is stored in multiple availability zones in a redundant manner. It can be used to protect data security and availability in the event of faulty operations, attacks or tampering.

CBS uses the copy-on-write (CoW) strategy to make the snapshot, eliminating the concern over business interruption caused by reduced disk performance during snapshot creation. In addition, automatic snapshot creation can be set up based on the business characteristics to back up the business data stored in blocks. If data loss or inconsistency occurs due to faulty operations, attacks or tampering, rollback can be performed for the snapshot to restore the data to the business status at the point in time of the snapshot. Plus, snapshot enables you to quickly copy data to a new server for rapid batch deployment or business migration. In the gaming industry, snapshots can be used to create CBS volumes for quick deployment in dozens of service areas, fully sustaining high numbers of requests during day 1 server launch for public trial and greatly reducing the labor costs for OPS.

Guaranteed High Reliability

With CBS, data is automatically stored in three cross-rack copies in an availability zone, ensuring that any single point of disk failure will not affect the reliability of the data. For the purpose of cross-resource pool disaster recovery, Tencent Cloud has isolated the CBS system and the snapshot system by deploying them in different data centers. Additionally, the system cannot be accessed from public networks, completely blocking malicious attacks. In the same data center, CBS data and snapshot data are stored in different racks, eliminating the possibility of business interruption due to power or ventilation failure of any single rack. Even in extreme cases where all the redundant copies of data in the CBS system are lost, it is guaranteed that the data can be recovered from the snapshot system.

Flexible Billing

CBS is pay-as-you-go. In this flexible billing mode, CBS volumes can be activated/terminated at any time and charged based on the actual usage. Billing is on a per second level and charged hourly, making it especially suitable for scenarios such as ecommerce flash-sales where business needs can significantly fluctuate instantaneously.


Hardware failures in traditional storage systems can cause serious business interruptions for dozens of hours. CBS efficiently supports hot migration for virtual machines to prevent such type of interruptions in advance. With comprehensive capabilities of data backup, snapshot and data recovery, it is suitable for high-load and core business-critical systems, helping meet the needs of corporate office applications for elastic and reliable large-capacity block storage.

Core business databases have to sustain intensive access requests during peak application hours, which requires continuous and stable high performance and low latency for the disks. Based on full SSD storage media and distributed architecture, the SSD cloud disk option of CBS features superior performance and high reliability, which helps meet the demanding requirements for performance in SQL scenarios, support high-throughput database requests of the business and satisfy the high IO needs of NoSQL/relational databases with ease.

High-IO storage scenarios of data analytics often require extremely high throughput for the storage system. With excellent multi-thread access performance, CBS can efficiently support Hadoop-Mapreduce and HDFS for processing terabytes or petabytes of data offline, making it ideal for many fields such as data analytics, data mining and business intelligence.


CBS provides two billing options to meet different customer needs: monthly subscription and pay-as-you-go. The monthly subscription mode is an upfront payment (unit: USD/GB * month). A minimum one month purchase is required. It's suitable for businesses with stable and long-term demands. The pay-as-you-go mode is an hourly settlement (unit: USD/GB * hour) that freezes fees for one billing cycle upon purchase. This option enables you to purchase or release resources at any time, making it suitable for business where the demand fluctuates significantly, such as flash sale campaigns on an e-commerce site.

For more information, see Product Pricing.