With the increasing demand for storage capacity and the need for maintenance convenience, computer systems have developed from simple internal storage to external storage, which is the mainstream network storage technology .
Moreover, with the rapid development of information technology, network storage technology plays an increasingly important role in data storage and management, which plays a role in improving data storage and management efficiency, reducing data storage costs, ensuring data security, supporting cross-platform use and Various functions to meet the needs of different application scenarios.
The IT Bear Bureau sorted out the characteristics of the four network storage technologies, DAS, SAN, NAS, and OBS, and finally made a summary and comparison table~ I don’t know which one is the yyds in your heart for you in front of the screen?
1. DAS
DAS is the earliest and most direct connection storage method. Connecting a data storage device and an application server through a bus adapter (SCSI/FC) constitutes the simplest DAS system .
Note: Schematic diagram of DAS structure
The implementation of DAS can be divided into two types, one is through SCSI cable (small computer system interface), and the other is through fiber channel (fiber channel, FC).
Among them , SCSI is used for the connection between the internal I/O channel of the server and the I/O channel of the storage system. Then transfer data through the conversion of I/O channel protocol and SCSI protocol.
According to different connection methods, SCSI can also be divided into serial SCSI (serial attached SCSI, SAS) and parallel SCSI. SCSI-3 is the representative of parallel SCSI with faster transmission speed.
However, no matter how good the SCSI protocol is, it cannot save the fate of DAS.
Due to the mode in which different types of DAS servers are connected to separate storage devices, storage resources cannot be shared. When people share data, they need cross-platform access and face data security and other issues.
Although arranging a computer to save shared files can temporarily solve some needs, the additional overhead is not a long-term solution for the company after all.
Not to mention, different servers face different amounts of stored data, the storage space cannot be fully utilized, and resources are wasted.
Therefore, in terms of practical application, DAS is more suitable for small enterprises to store data in the network.
Two, SAN
With the development of network technology and the continuous growth of user data, the disadvantages of DAS are becoming more and more obvious. In order to solve the problems of poor scalability, decentralized management and difficulty in sharing, SAN has emerged.
SAN implements multiple servers to share storage devices, and consists of a storage device and various system components, including servers using storage device resources, storage area network switches, and host bus adapters (HBA).
Note: SAN structure diagram
According to different implementation forms, SAN can be divided into three types: FC-SAN, IP-SAN and SAS-SAN. They adopt different communication protocols and connection methods respectively.
Among them, FC-SAN uses Fiber Channel Protocol (FCP, which is equivalent to the implementation of SAS on FC network) to realize data transmission, which has the characteristics of high-speed transmission and high scalability. FC-SAN is connected through components such as fiber optic switches, FC HBA cards, and FC-compatible storage devices. However, due to the high price and complicated configuration of these devices and components, many small and medium users are discouraged.
There are many protocols that IP-SAN can use, including iSCSI, FCIP, and iFCP, etc., but most of them are based on iSCSI protocol, a standardized protocol based on TCP/IP protocol and SCSI instruction set. The connection components of IP-SAN usually only need to adopt ordinary Ethernet card/iSCSI HBA card, Ethernet switch and storage device supporting iSCSI.
Note: 3 networking connection methods of IP-SAN
Because IP-SAN uses the widely used and relatively cheap IP network as the connection technology, it also greatly reduces the total cost of ownership. It is not only easy to maintain, but also convenient for subsequent expansion and network expansion.
In practical applications, there are many cases of combining FC-SAN and IP-SAN.
For example, Huawei's OceanStor V3 series unified storage products use the flexible networking mode of FC and iSCSI to meet the centralized storage of application systems with different performance requirements. The schematic diagram is as follows:
The SAS-SAN that appeared later can also be regarded as a dark horse. Its SAS can not only stand side by side with FC, but also compatible with SATA. Its storage principle and structure are similar to those of the former two, but the access speed has been improved on the basis of IP-SAN, and the compatibility is the best among the three, and the price is much lower than that of FC-SAN. It has become the first choice of "cost-effective" for users.
3. NAS
Unlike SAN, which uses block-level data as the basic access unit, NAS has established a data center based on file storage and sharing, with large-scale, centralized storage management as the trend, also known as "file sharing server" and "network file storage" . device" .
The reason why it is called so is because NAS has its own node on a LAN, without the participation of application servers, allowing users to directly share and access file data through the network.
Note: Schematic diagram of NAS structure
Therefore, NAS also has a different composition structure from SAN. It is similar to the basic structure of a computer. The hardware part consists of a core controller (including processors, memory, network adapters, and disk interfaces) and a storage subsystem (usually using disk arrays);
According to the function, the software part can be divided into five modules: operating system, volume manager, file system, network file sharing and web management.
Traditional NAS servers use Ethernet and TCP/IP protocols to communicate and share files with Unix/Linux or Windows systems through file systems NFS or CIFS respectively.
Generally speaking, NAS has a different service mode from SAN, so it has a wide range of application scenarios, such as the information document sharing of office OA, the data management needs of medical imaging systems in the medical field, and the needs of a large number of resource information on campus networks. NAS can be used to solve.
However, when faced with a large number of storage operations, NAS devices share the local area network——LAN for business use with network servers and user clients. Its performance is likely to become a system bottleneck and reduce the operating speed of other systems. In this regard, NAS is indeed inferior to SAN .
Therefore, in order to improve the capacity, performance, availability and reliability of storage, more and more attention has been paid to the combination scheme of "SAN+NAS engine" . It can be said that the two achieve each other.
For example, OceanStor N8500, a unified storage device used in NAS&SAN integrated network, is also a clustered mid-to-high-end NAS storage system for multiple industries. Its location and application are shown in the following figure:
This storage device not only meets the needs of efficient data sharing products, but also has flexible horizontal and vertical scalability. Its applications can cover businesses in multiple industries such as the Internet/government/finance/entertainment and media.
4.OBS
With block-level SAN and file-level NAS, let’s talk about object-oriented OBS, a new storage architecture (strictly speaking, OBS does not completely belong to network storage technology. were included for meaningful comparison).
OBS is an object storage technology , which can be regarded as a technology that stores data on multiple computers, and writes data to the storage network of multiple devices at the same time through the network.
The object here refers to the combination of files and blocks . Therefore, it can be accessed through the interface and share data between different platforms like a file, or it can be directly accessed in a storage device like a block without going through a server. According to different purposes, objects can be divided into root objects, partition objects, user objects, and collection objects.
A typical object storage system consists of a user terminal (client), a metadata server (MDS) and an object storage server (OSS), which are connected through high-speed Ethernet or independent wiring , and perform data communication based on the standard SCSI-3 command set.
Note: storage system based on object storage
The OSS is a server node running on the relevant file system, each OSS exports one or more object storage targets (OST), and finally the OST allocates and stores the object data to the OSD (object storage device).
Compared with NAS, the advantages of OBS are mainly reflected in the processing of metadata. Since the file data of NAS is stored on multiple nodes, the more storage nodes there are, the more metadata the NAS server needs to process, which limits NAS The size of storage. On the other hand, 90% of OBS metadata exists in OSD, which is managed by the device itself, so there is no bottleneck in metadata processing.
Compared with SAN , the scalability of OBS is stronger. SAN is mainly affected by the traditional framework. The storage array is independent of LAN and needs to be wired in the data center. The host controls the hard disk configuration. When users configure SAN, The reserved expansion space has basically been determined. As the requirements for data storage increase, this inelastic framework becomes an obstacle to expansion. However, OBS can be expanded by modifying the configuration, adding nodes, and connecting OSD to the network, and has good scalability.
Not only that, OBS also combines the advantages of NAS and SAN - high-speed access, high sharing, high performance, easy management and high security.
However, OBS technology is still in the development stage, so relatively speaking, the software and hardware that can provide support are not perfect enough.
Technical application case: Alibaba Cloud makes good use of OSS object storage to provide massive, safe, low-cost, and highly reliable cloud storage services. Compared with self-built storage, OSS has outstanding advantages in ease of use, persistence and data security.
Taking the mass storage of Alibaba Cloud OSS in applications such as pictures, audio and video as an example , OSS can be used to store mass files such as pictures, audio and video, and logs. Various terminal devices, web site programs, and mobile applications can directly write or read data to OSS. OSS also supports stream writing and file writing.
Note: Schematic diagram of mass storage for applications such as pictures and audio and video
Not only that, Alibaba Cloud OSS also provides a variety of data processing capabilities, such as image processing, video frame capture, document preview, image scene recognition, SQL query, etc., to achieve intelligent storage.
write at the end
Today, the storage system is as important as computing and transmission. It is the three cornerstones of the Internet, and network storage is the core field of informatization.
From DAS to SAN, and then to NAS, it not only represents different forms of network storage, but also represents different development stages of network storage technology . Object storage systems are more the result of an ongoing in-depth understanding of the architecture.
Each storage technology embodies the value of existence, no matter which type is picked, it is the result of on-demand services.
Finally, welcome to leave a message: talk about some network storage technologies used by your company~
Network storage technology brain map
*Part of the reference content in this article comes from the public domain of the Internet, and the copyright belongs to the original author. The reference sources are as follows:
https://support.huaweicloud.com/productdesc-obs/obs_03_0202.html
Wu Chengtao. "Information Storage and IT Management". People's Posts and Telecommunications Press. 2019.12
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