How to connect docker storage

With the rapid development of cloud computing and containerization technology, Docker has become one of the most popular containerization platforms. When using Docker to run containerized applications, persistent storage of data is an important issue. Docker storage provides various options for data storage and management. This article will explore Docker storage and how to connect it.

1. Docker storage

Docker uses a hierarchical joint file system as the file system of the container. This file system is based on the image, and the file system of the container is modified and modified on this basis. expanded. But as the number of containers increases, Docker storage becomes more and more important, because the data stored in the containers needs to be persisted.

Docker provides three storage drivers:

• aufs: a hierarchical file system based on the union file system. aufs can combine multiple file systems into one file system, and these file systems can exist independently of the host's file system. aufs requires kernel support.
• overlay: A hierarchical file system based on a federated file system. Compared with aufs, the advantage of overlay is that it does not require kernel support, but it may cause performance degradation in some cases.
• devicemapper: A storage driver that uses block device mapping technology. Devicemapper creates a block device when the container starts and uses this block device to store data in the container. devicemapper requires kernel support.

2. Docker storage connection

Docker storage connection is the process of connecting Docker's storage to the host's storage. In Docker, storage connections can be made in the following ways:

1. Data volumes

Data volumes are the most commonly used and flexible storage connection method in Docker. A data volume is a directory or file that can be mounted into a container, and the container can read and write the data in this directory or file. The data volume can be a directory or file in the local file system or a directory or file in an external storage system.

By using data volumes, the host's directories or files can be mounted inside the container when the container is started, so that the container can read and write data through these directories and files. At the same time, because the data volume is reusable, multiple containers can share the same data volume.

2. Bind mounts

A mount point is a host directory or file that can be mounted inside a container. The difference between it and a data volume is that the data volume is automatically created by Docker, and the mount point must be a directory or file that exists on the host.

By using the mount point, the host directory or file can be mounted inside the container, and this directory or file can be read and written by the container. Since the mount point exists on the host, only directories or files that exist on the host can be mounted inside the container. The difference from data volumes is that the mount point does not need to be defined in the Dockerfile and can be specified when running the container.

3. tmpfs mounts

tmpfs is a memory file system that can be mounted inside a container. Use tmpfs to create a temporary directory or file in the container and save this directory or file in memory.

By using tmpfs, you can create a temporary directory or file in the container and save the directory or file in memory to avoid writing data to disk. The difference from data volumes and mount points is that tmpfs only exists in memory and is not saved to disk. Therefore, when the container is stopped or restarted, data is lost.

3. Summary

Docker storage is a very important part of Docker. When using Docker containerized applications, you need to consider the issue of persistent storage of data. Docker provides three storage drivers and multiple storage connection methods. We can choose the most appropriate storage driver and storage connection method according to actual needs.

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