Alibaba Cloud Object Storage Service (OSS) is a massive, secure, low-cost, and highly reliable cloud storage service provided by Alibaba Cloud. It has a platform-independent RESTful API interface, capable of providing 99.999999999% (11 9s) data reliability and 99.95% service availability. You can store and access any type of data in any application, anytime, anywhere.
You can use the API/SDK interface provided by Alibaba Cloud or the OSS migration tool to easily move massive data into or out of Alibaba Cloud OSS. After data is stored in Alibaba Cloud OSS, you can choose the standard Alibaba Cloud OSS service as the main storage method for mobile applications, large websites, image sharing, or hot audio and video, or you can choose lower cost and longer storage periods. Alibaba Cloud OSS services of the infrequent access type (Infrequent Access) and the archive type (Archive) are used as backup and archive of infrequently accessed data.
1 Object Storage:
Generally speaking, object storage has both the advanced direct access disk characteristics of SAN and the distributed sharing characteristics of NAS.
The core is to separate the data path (data read or write) and control path (metadata), and build a storage system based on an object storage device (OSD). Each object storage device has certain functions and can automatically manage the data on it. distributed.
Object storage structure components (objects, object storage devices, metadata servers, clients of object storage systems)
1.1 Objects
An object is actually a combination of file data and a set of attribute information.
1.2 Object Storage Device (OSD)
OSD has a certain intelligence, it has its own CPU, memory, network and disk system.
The OSD provides three main functions: including data storage and secure access
(1) Data storage (2) Intelligent distribution (3) Management of metadata for each object
1.3 Metadata Server (Metadata Server, MDS)
MDS controls the interaction between Client and OSD objects, and mainly provides the following functions:
(1) Object storage access
Allows the client to directly access the object. When the OSD receives the request, it verifies the capability before accessing it.
(2) File and directory access management
MDS builds a file structure on the storage system, quota control, including directory, file creation, access control, etc.
(3) Client Cache consistency
To improve performance, the client's Cache is usually supported when the object storage system is designed. Therefore, the problem of Cache consistency is brought about. When the Cache file changes, the Client will be notified to refresh the Cache to prevent problems caused by Cache inconsistency.
Object storage:
A file contains attributes (termed matadata metadata, such as the file size, modification time, storage path, etc.) and content (referred to as data).
In the previous file system, the stored procedure shredded the file according to the smallest block of the file system, and then wrote it to the hard disk, without distinguishing between metadata and data in the process. The address of the next block will be notified at the end of each block, so it can only be read one by one, which is slow.
The object storage separates the metadata, and the control node is called the metadata server (server + object storage management software), which mainly stores the attributes of the object (mainly the data of the object is scattered and stored in the distributed servers). information), while other distributed servers responsible for storing data are called OSDs, which are mainly responsible for storing the data part of the file. When a user accesses an object, it will first access the metadata server, and the metadata server is only responsible for returning objects stored in those OSDs. Assuming that the feedback file A is stored in the three OSDs B, C, and D, the user will visit the three OSD servers again to read the data.
At this time, the three OSDs transmit data at the same time, so the transmission speed is accelerated. The greater the number of OSD servers, the greater this increase in read and write speed.
On the other hand, the object storage software has a special file system, so the OSD is equivalent to a file server to the outside world, so there is no difficulty in file sharing, and the problem of file sharing is also solved.
Therefore, the emergence of object storage is a good combination of the advantages of block storage and file storage.