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This article is about the difference between object storage and block storage on the Internet. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

Differences: 1, different users, block storage users are software systems that can read and write block devices; object storage users are other computer software. 2. Different speed, fast storage is low latency (10ms), while object storage is "100ms-1s"; 3, different interfaces; 4, suitable for different scenarios.

The operating environment of this tutorial: windows7 system, Dell G3 computer.

Block storage

Typical devices: disk array, hard disk

Block storage mainly maps the entire bare disk space to the host.

That is to say, for example, there are 5 hard drives in the disk array, and then N logical hard drives can be logically divided by dividing the logic disk, doing Raid, or LVM, etc. But logical disk and physical disk are two completely different concepts. Suppose that each hard disk 100g, a total of five hard disks, divided into five logical disks, each 100g, but the meaning of these five logical disks is completely different from the original five physical disks. For example, the first logical disk the first 20G may come from physical disk 1, and the second 20G may come from physical disk 2, so the logical disk is a hard disk made up of multiple physical disk logic.

Block storage will then map these logical disks to the host by mapping, and the operating system on the host will recognize that there are five hard disks, but the operating system cannot tell whether it is a physical disk or a logical disk. It simply thinks that they are only five naked physical hard disks, which is no different from directly mounting a physical hard disk to the operating system, at least in the perception of the operating system.

In this way, the operating system also needs to partition and format the mounted bare hard disk before it can be used, which is no different from the built-in hard disk of the ordinary host.

Advantages

(1) the advantage of this approach is, of course, that data is protected by means such as Raid and LVM.

(2) multiple cheap hard drives can be combined, which is called a large-capacity logical disk to provide services, thus increasing the capacity.

(3) when writing data, because it is a logical disk composed of multiple disks, several hard disks can be written in parallel, which improves the efficiency of reading and writing.

(4) in many cases, block storage uses SAN architecture to network, transmission speed and encapsulation protocol, so that the transmission speed and read and write efficiency are improved.

Shortcoming

(1) when using SAN architecture to build a network, it is necessary to purchase additional fibre Channel cards and fiber switches for the host, which is of high cost.

(2) data cannot be shared between hosts. If the server does not cluster, the bare disk of block storage is mapped to the host. After formatting, it is equivalent to the local domain for the host. Then the local disk of host A cannot be used by host B at all, and the data cannot be shared.

(3) it is not conducive to data sharing between hosts of different operating systems: because the operating system uses different file systems, after formatting, the data between different file systems cannot be shared. For example, for a win7, the file system is FAT32/NTFS, and linux is a file system that EXT4,EXT4 does not recognize NTFS.

file store

Typical equipment: FTP, NFS server

In order to overcome the problem that files cannot be shared, there is file storage.

File storage also has software and hardware integration equipment, but in fact, an ordinary PC, as long as installed with the appropriate operating system and software, you can assume that FTP and NFS services, the server after the installation of such services, is a kind of file storage.

Host A can upload and download files directly to the file storage. Unlike block storage, host A no longer needs to format the file storage, because the file management function has been completed by the file storage itself.

Advantages

(1) low cost: any machine is fine, and ordinary Ethernet is fine. There is no need for a dedicated SAN network at all, so the cost is low.

(2) facilitate file sharing

Shortcoming

(1) low read and write rate, slow transmission rate: Ethernet, upload and download speed is slow, in addition, all read and write have to be borne by the hard disk in a server, compared with the disk array, the speed is much slower than a dozen or hundreds of hard drives at the same time.

Object storage

Typical equipment: distributed server with built-in high-capacity hard disk

The most commonly used scheme of object storage is that multiple servers have built-in large-capacity hard drives, then install object storage software, and then set up a few additional services as management nodes, and install object storage management software. The management node can manage other servers to provide read and write access.

The reason for the emergence of object storage is to overcome the shortcomings of block storage and file storage and carry forward their respective advantages. To put it simply, block storage reads and writes quickly, which is not conducive to sharing, while file storage reads and writes slowly, which is conducive to sharing. Is it possible to get a read-write block to facilitate shared storage? As a result, there is object storage.

First, a file contains attributes (terminology: metadata, metadata, such as the file's size, modification time, storage path, and so on) and content (data).

Such as FAT32 file system, is to directly store a file with metadata, the stored process will first file in accordance with the minimum block size to break up (for example, 4m files, assuming that the file system requires a block 4K, then the file will be scattered as 1000 small blocks), and then write to the hard disk, there is no distinction between data and metadata. Each block will finally tell you the address of the next block to read, and then always follow the clues in this order, and finally complete the reading of all the blocks of the whole file.

In this case, the reading and writing rate is very slow, because even if you have 100 robotic arms reading and writing, you can't know where the next block is until you read the first block, which means that only one robotic arm is actually working.

The control node is called metadata server (server + object storage management software), which is mainly responsible for storing the attributes of objects (mainly the information that the object's data is scattered and stored in those distributed servers), while other distributed servers responsible for storing data are called OSD, which are mainly responsible for storing the data part of the file. When a user accesses an object, he will first access the metadata server. The metadata server is only responsible for feedback on where the object is stored in the OSD. Assuming that the feedback file An is stored in B, C and D OSD, then the user will directly visit the three OSD servers to read the data.

At this time, because there are three OSD transmitting data at the same time, the transmission speed will be accelerated. When there are more OSD servers, the speed of reading and writing will increase. In this way, the goal of fast reading and writing can be achieved.

On the other hand, object storage software has a special file system, so OSD is externally equivalent to a file server, so there is no difficulty in sharing, and the problem of file sharing is solved.

So the emergence of object storage combines the advantages of block storage and file storage.

Why does object storage have the benefits of both block storage and file storage, but also use block storage and file storage?

(1) there is a class of applications that need to store direct bare disk mapping, such as databases. Because the data needs to be mapped to itself, and then formatted according to its own database file system, it is not possible to use other storage that has been formatted into a certain file system. This type of application is more suitable for block storage.

(2) the cost of object storage is higher than that of ordinary file storage, so it is necessary to purchase special object storage software and large-capacity hard disk. If the requirement for a large amount of data is not massive, but just for file sharing, it is better to use the form of file storage directly, which is cost-effective.

The difference between block storage, file storage and object storage

Thank you for reading! This is the end of the article on "what's the difference between object storage and block storage on the Internet". I hope the above content can be of some help to you, so that you can learn more knowledge. If you think the article is good, you can share it for more people to see!

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