FastDFS

FastDFS is an open source lightweight distributed file system. It manages files. Its functions include: file storage, file synchronization, file access (file upload, file download), etc., which solves the problem of mass storage and load balancing. It is especially suitable for online services with files as the carrier, such as photo album websites, video websites and so on.
The FastDFS server has two roles: tracker and storage node. The tracker mainly does scheduling work and plays the role of load balancing in access.
The storage node stores files and completes all the functions of file management: storage, synchronization and providing access interfaces. FastDFS also manages the metadata of the files. The so-called meta data of a file is the related attributes of the file, expressed in the form of key value pairs, such as width=1024, where the key is width and the value is 1024. File metadata is a list of file attributes, which can contain multiple key-value pairs.
Both tracker and storage nodes can consist of one or more servers. Servers in both tracker and storage nodes can be added or taken offline at any time without affecting online services. All servers in the tracker are peer-to-peer and can be increased or decreased at any time according to the stress of the server.
To support large capacity, storage nodes (servers) are organized in volumes (or groups). A storage system consists of one or more volumes. The files between volumes are independent of each other. The cumulative file capacity of all volumes is the file capacity of the entire storage system. A volume can be composed of one or more storage servers. The files in the storage servers under a volume are all the same. The multiple storage servers in the volume play the role of redundant backup and load balancing.
When adding a server to the volume, the system will automatically complete the synchronization of existing files. After the synchronization is completed, the system will automatically switch the newly added server to provide services online.
Volumes can be added dynamically when storage space is running out or is about to run out. Just add one or more servers and configure them as a new volume, thus expanding the capacity of the storage system.