Tencent Cloud provides a wide range of flexible and cost-effective data storage devices for CVM instances. The performance and price varies by the type of storage device, which is suitable for different scenarios.
Storage Devices
Storage devices can be divided into the following categories by dimension:
Dimension
Category
Description
Storage Medium
HDD disk
Uses hard disk drive (HHD) as the storage medium. It features a low price and fast read/write speeds.
SSD disk
Uses solid state drive (SSD) as the storage medium. It features excellent IOPS and read/write speeds, with an IOPS and throughput of up to 20 times and 16 times higher than those of the HDD disk. It is more expensive than the HDD disk.
Use Cases
System disk
Used to store the collection of systems that control and schedule the operation of CVM. It uses images.
Cloud Block Storage (CBS) is an elastic, highly available, highly reliable, low-cost, and customizable network block device that can be used as a standalone scalable disk for CVM. It provides data storage at a data block level and employs a 3-copy distributed mechanism to ensure data reliability.
You can adjust the hardware, disk, and network of a CVM with CBS.
Cloud Object Storage (COS) is a data storage device on the Internet. It allows data retrieval from any location on the CVM instance or the Internet, reducing storage costs. It is unsuitable for low-latency and high-IO scenarios.
Block storage device mapping
Each instance has a system disk to ensure basic data operations, and may mount more data disks. An instance uses block storage device-mapping to map the storage devices to locations it can identify.
CBS puts data into blocks in bytes and allows random access. Tencent Cloud supports two types of CBS devices: local disk and cloud disk.
This figure shows how CBS maps the block storage device to the CVM: it maps /dev/vda to the system disk and maps the two data disks to /dev/vdb and /dev/vdc, respectively.
The CVM instance can automatically create block storage device mapping for local disks and cloud disks mounted to itself.
