When configuring an instance, you can choose a local disk or a cloud disk as your system disk or data disk. Before you choose a storage media, please familiarize yourself with the characteristics and the use cases of local disks and Cloud Block Storage.
- The types of system disks and data disks on the purchase page vary by the different instance specifications you select. For example, SSD local disks are only available for IO instances.
- You cannot upgrade the hardware (CPU, memory, or storage) of a CVM instance with local disks. You can only upgrade its bandwidth.
- The media type of system disks cannot be changed after purchase.
The following table lists the different strengths and use cases of different storage media such as the SATA HDD local disk, the NVME SSD disk, Premium Cloud Storage, and SSD.
|Storage Media||Strengths||Use Cases|
|NVME SSD local disks (only available for IO instances such as IT3 and IT5)||Low latency: provides microsecond-level access latency.||Acts as a temporary read cache: NVME SSD has excellent random read performance (4 KB/8 KB/16 KB random read) and is suitable for read-only slave databases for relational databases such as MySQL and Oracle.
Since the cost of using memories is still higher than the cost of using SSDs, NVME SSD local disks can also be used as the secondary cache of Redis, Memcache, and other cache business.
Note: NVME SSD carries the risk of a single point of failure. Therefore, we recommend that you implement data redundancy at the application layer to ensure reliability and use SSD cloud disks for your core business.
|SATA HDD local disk (only available for big data instances such as D2)||
||It is suitable for scenarios that involve the sequential reading and writing of large files, such as EMR and big data processing.|
|Premium Cloud Storage||It is the most cost-effective option that is suitable for 90% of I/O scenarios.||It is suitable for small and medium databases, web servers, and other scenarios, and provides consistent and stable I/O performance.
It meets the I/O demands for testing core business and developing joint testing environments.
|SSD||High performance and high data reliability: SSD uses the best-in-class NVMe solid state storage as the disk media. It is suitable for I/O-intensive business and provides long-term and ultra-excellent single disk performance.||Applicable use cases: