We provide various types of data storage devices that are flexible, economical, and easy to use for Cloud Virtual Machine instances. Different storage devices have different performance and prices and are suitable for different use cases.
Storage device classification
Storage devices can be divided into the following categories according to different classification dimensions.
| Division dimensions | Classification | Note |
|---|---|---|
| Storage Media | General Hard Disks | The storage medium is a mechanical hard disk. Its characteristics are low price and better reading and writing speed. |
| Storage Media | SSD Hard Disks | The storage medium is a solid state drive (SSD). It is characterized by excellent performance in IOPS and reading and writing speed, and can achieve up to 20 times the IOPS and 16 times the throughput of ordinary hard disks. The price is higher than ordinary hard disks. |
| Storage Media | Efficient cloud disk | Mixed storage types. It is suitable for small and medium-sized use cases such as Web/App servers, business logic processing, and small and medium-sized website construction with high data reliability requirements and ordinary moderate performance requirements. |
| Application Scenario | System Disk | A collection of systems used to store, control, and schedule Cloud Virtual Machine operations by using images. |
| Application Scenario | Data Disk | Used to store all user data. |
| Architecture Patterns | Cloud Block Storage | Cloud Block Storage is a flexible, highly available, highly reliable, low-cost, customizable network block device that can be used as an independent, scalable hard disk for the Cloud Virtual Machine. It provides data block-level data storage and adopts a three-copy distributed mechanism to ensure data reliability for CVM. If the CVM has a Cloud Block Storage, the hardware, disk, and network can be adjusted. |
| Architecture Patterns | Local Disk | The local disk is a part of the local storage of the physical machine where the CVM instance is located. It is a storage area of the local storage of the physical machine where the CVM instance is located. Data access can achieve lower latency, but there is a risk of single point failure of data. The hardware (CPU, memory, and disks) upgrade is not available for the CVM that uses local disks, but the bandwidth upgrade is supported. |
| Architecture Patterns | Cloud Object Storage | Cloud Object Storage is a data storage device located on the Internet that supports retrieval of data from a Cloud Virtual Machine instance or anywhere on the Internet, thereby reducing storage costs. Not suitable as a storage medium for low-latency, high-IO scenes. |
Block storage device mapping
Each instance has a system disk to ensure basic operating data, and more data disks can be mounted to the instance. Instances use block storage device mapping to map these storage devices to locations that they can recognize.
Block storage is a storage device that is divided into blocks of bytes and supports random access. The cloud platform supports two types of block storage devices, that is, local disks and Cloud Block Storage.
This figure shows how CBS maps block storage devices to the Cloud Virtual Machine: Map /dev/vda to the system disk, and map the two data disks to /dev/vdb and /dev/vdc.
The Cloud Virtual Machine instance automatically creates block storage device mappings for local disks and Cloud Block Storage mounted to the instance.