Three common storage technologies are clarified: Das, San, and NAs.

With the increase in the time and data volume of enterprise network applications, enterprises have already felt that storage capacity and performance are lagging behind and network application development needs, especially for streaming media enterprises, the emergence of technical applications that meet users' storage needs under such conditions has led to the emergence of three storage technologies: Das, NAS, and San.

I found that my knowledge is still very scarce. First of all, I would like to summarize the basic knowledge. Of course, these are the materials stored on the Internet. Originality does not belong to the author, this is to analyze the storage knowledge. I hope I can discuss storage with more people and learn more.

Today, let's take a look at the storage categories. Server types are classified into: closed system storage and open system storage. Closed System mainly refers to the mainframe, an open system is a server based on Windows, UNIX, Linux, and other operating systems. The storage of an open system is divided into internal storage and external storage. The external storage is divided: direct-Attached Storage (DAS) and fabric-Attached Storage (FAS); network storage is divided: network-Attached Storage (NAS) and storage area network (SAN ).

Is it a bit messy? Let's take a look at the image below, so it may be clearer.

Das Storage

Das storage is very common in our lives, especially in small and medium-sized enterprises. Das is the most important application model. The storage system is directly connected to the Application Server. in small and medium-sized enterprises, many data applications must be installed on directly connected das memory.

Das stores more Io reads, writes, and stores and maintains data based on the server host operating system. data backup and recovery require occupying server host resources (including CPU and system Io ), data streams need to be streamed back to the host and then to the tape drive (database) connected to the server. Data Backup usually occupies 20-30% of the server host resources, therefore, the daily data backup of many enterprise users is often performed late at night or when the business system is not busy, so as not to affect the normal operation of the business system. The larger the data volume of direct-connection storage, the longer the backup and recovery time, and the greater the dependency and impact on server hardware.

The connection channel between direct-connection storage and server hosts usually uses SCSI connections. As the server's CPU processing capability is getting stronger and stronger, the storage hard disk space is getting larger and the number of hard disks on the array is increasing, the SCSI channel will become an IO bottleneck; the server host's scsi id resources are limited, and the SCSI channel connections that can be established are limited.

Regardless of direct-connection storage or server host expansion, expansion from a server to a cluster composed of multiple servers, or expansion of storage array capacity, will cause business system downtime, this results in economic losses to enterprises. This is unacceptable for key business systems that provide services in banking, telecommunications, media, and other industries. In addition, the upgraded and extended direct-connection storage or server host can only be provided by the original device manufacturer, which is often limited by the original device manufacturer.

NAS Storage

NAS storage is also known as additional storage. as its name implies, storage devices are added to a group of computers through standard network topologies (such as Ethernet. NAS is a file-level storage method, and its focus is to help working groups and department-level organizations to quickly increase storage capacity. Nowadays, many NAS functions are used for file sharing, image sharing, and movie sharing. With the development of cloud computing, some NAS vendors have also released cloud storage functions, this greatly facilitates the use of enterprises and individual users.

NAS products are truly plug-and-play products. NAS devices generally support multi-computer platforms. Users can access the same document through network support protocols. Therefore, NAS devices can be used in a hybrid UNIX/Windows nt lan without any need for transformation, at the same time, NAS applications are flexible.

However, NAS is another critical issue, namely the bandwidth consumption during Backup. Unlike the storage area network (SAN) that transfers backup data streams from the LAN, NAS still uses the network for backup and recovery. One disadvantage of NAS is that it transfers storage transactions from parallel SCSI connections to the network. This means that the lan must not only process normal end user transmission streams, but also handle storage disk requests including backup operations.

SAN storage

From the name of the storage Region network, we can also see that this is to connect the storage array and server host through the Fiber Channel switch, and finally become a dedicated storage network. After more than a decade of development, San has become quite mature and a de facto standard in the industry (however, different vendors have different fiber-optic switching technologies, and their servers and SAN storage have compatibility requirements ).

San provides an easy way to connect to an existing LAN and supports a wide range of SCSI and IP protocols through the same physical channel. San is not subject to the current mainstream SCSI-based storage structure layout restrictions. It is particularly important that with the explosive growth of storage capacity, SAN allows enterprises to independently increase their storage capacity. The San structure allows any server to connect to any storage array, so that no matter where the data is stored, the server can directly access the required data. Because the optical fiber interface is used, San also has higher bandwidth.

Because the San solution separates the storage from basic functions, you do not need to consider the impact of the San solution on the overall network performance when running backup operations. The San solution simplifies management and centralized control, especially when all storage devices are clustered together. Finally, the optical fiber interface provides a connection length of 10 kilometers, which makes it easy to physically separate and store data outside the data center.

Summary: In the end, the DAS storage is generally used in small and medium-sized enterprises. It is directly connected to the computer, NAS storage is added to the computer through Ethernet, and SAN storage uses the FC interface, provides better storage performance. The main difference between NAS and NAS is the location of the operating system, as shown in.

Nowadays, with the advent of the mobile computing era, more unstructured data is generated, which poses a challenge to NAS and San. NAS + San will be the main storage solution in the future, that is, the popular Unified Storage. Since it is a centralized disk array, it supports file-level data access by the host system through the IP network, or block-level data access through the optical fiber protocol in the San network. ISCSI is also a very common IP protocol, but it provides block-level data access. This disk array is configured with a multi-port storage controller and a management interface that allows the storage administrator to create a storage pool or space as needed and provide it to host systems of different access types.

Unified Storage System: front-end host interfaces support FC 8 GB, iSCSI 1 GB, and iSCSI 10 Gb, and the back-end supports SAS 6 GB hard disk expansion interfaces, it supports SAS, SATA, and ssd ssds with excellent scalability. It perfectly integrates FC San with IP San and various storage media, effectively integrates users' existing storage network architecture, and achieves unified deployment and centralized management of high-performance San networks, to adapt to the dynamic needs of business and application changes. Both the host interface and hard disk interface adopt modular design. Replacing the host interface or hard disk expansion interface can greatly simplify the difficulty and workload of upgrading and maintaining without changing the firmware.

Three common storage technologies are clarified: Das, San, and NAs.