When configuring an instance, you can select a local disk or Cloud Block Storage (CBS) as your system disk or data disk. Before selecting a storage medium, please understand the characteristics and differences in applicable scenarios between local disks and CBS.
- The types of system disks and data disks that can be purchased on the purchase page vary by the instance specifications you have selected. For example, only users who choose a high IO instance type can choose a local SSD.
- CVMs that use local disks (including system disks and data disks) do not support configuration upgrades (CPU, memory, and hard disk), but only bandwidth upgrades.
- After successful purchase, the system disk does not support storage media replacement.
The differences and applicable scenarios of storage media (local SSD, Basic Cloud Disk, Premium Disk and Cloud SSD) are shown in the following table:
| Storage Media | Strengths | Applicable Scenario |
|---|---|---|
| Local SSD | Low delay: Provides microsecond-level access delay. | Used as temporary read cache: Local SSD has excellent random read performance (4 KB/8 KB/16 KB random read), and is suitable as a read-only slave database for relational databases such as MySQL and Oracle. The memory cost is still higher than that of SSD. Therefore, Local SSD can also serve as the secondary cache for cache-based services such as redis and Memcached. Note: Local disks have the risk of single point failure. It is recommended to perform data redundancy at the application layer to ensure data availability. It is recommended to use Cloud SSD for core businesses. |
| Basic Cloud Disk | Low-cost storage with the same data persistence as Cloud SSD. It can be used for cold data backup and archiving of important business. The single disk capacity is up to 16 TB. | Suitable for sequential reading and writing of large files, such as log flow, streaming media services, data warehousing, etc., to meet the needs of offline analysis of TB-level and massive data under the Hadoop framework. |
| Premium Disk | Suitable for 90% of I/O scenarios, providing the best choice with high quality and low costs. | Suitable for scenarios such as small and medium-sized databases, web servers, providing long-term stable I/O performance output. Meeting the I/O requirements of core business testing and development and debugging environments. |
| Cloud SSD | High performance and high data reliability: Use the industry's best NVMe solid-state storage as the disk media. It is suitable for I/O-intensive businesses and provides long-term stable and ultra-high single-disk performance. | Applicable to the following scenarios: - Medium and large databases: It can support medium and large-sized relational database applications such as MySQL, Oracle, SQL Server, MongoDB, etc. with millions of rows in tables. - Core business system : Core business systems such as I/O intensive systems that have high requirements for data reliability. - Big data analysis: Provides distributed processing capabilities for TB and PB-level data, suitable for data analysis, mining, business intelligence and other fields. |