Detailed Explanation of Network Storage Technology

Detailed Explanation of Network Storage Technology

Network storage technology is generally divided into three types: NAS, SAN, and DAS:

NAS Network Storage

1. Maximum storage capacity

The maximum storage capacity refers to the limit of the data storage capacity of the NAS storage device. In layman's terms, the maximum number of hard disks that the NAS device can support multiplied by the capacity of a single hard disk is the maximum storage capacity. This value depends on the hardware specifications of the NAS device. Different hardware levels have different applicable scopes, and the storage capacity is also different. Usually, a small NAS storage device will support a storage capacity of several hundred GB, which is suitable for small and medium-sized companies to use as a storage device for sharing data, while mid-to-high-end NAS devices should support T-level capacity (1T=1000G).

2. Processor

Similar to ordinary computers, NAS products also have their own processor (CPU) system to coordinate and control the normal operation of the entire system. The processors they use are often roughly the same as the CPUs of desktop computers or servers. Currently, there are mainly the following categories.

(1) Intel series processors

(4) AMD series processors

(5) PA-RISC processor

(6) PowerPC processor

(7) MIPS processor

Generally, NAS products for small and medium-sized companies use AMD processors or Intel PIII/PIV processors. NAS products for large-scale applications use Intel Xeon processors or RISC processors. However, this cannot be generalized, as it depends on the specific application and manufacturer's planning.

3. Memory

NAS is a streamlined computer in terms of structure. Each NAS device is equipped with a certain amount of memory, and most users can expand it later. In NAS devices, common memory types include SDRAM (synchronous memory) and FLASH (flash memory). Different NAS products are equipped with different memory capacities when they leave the factory, generally ranging from tens of megabytes to several GB (1GB=1000MB), depending on the application scope of the NAS product. Generally speaking, for NAS used in a small-scale local area network, if it only handles the access of a few devices, a memory capacity of less than 64M is sufficient. If it is accessed by more than a hundred nodes, a memory capacity of more than G is required. Of course, this is not an absolute factor. The comprehensive performance of NAS products also depends on the constraints of its processor power, hard disk speed and its actual network environment. In short, when purchasing NAS products, performance parameters of various aspects should be considered comprehensively.

4. Interface

The external interface of NAS products is relatively simple. Since they communicate with the outside world only through the built-in network card, they generally only have an Ethernet interface, usually RJ45 specifications, and this type of interface network card is generally a 100M network card or a 1000M network card. In addition, some NAS products need to connect to SAN (storage area network) products to provide more powerful functions, so they may also have FC (Fiber Channel) interfaces.

5. Pre-installed software system

Prefabricated operating systems refer to the operating systems or management software that come with NAS products when they leave the factory. Currently, NAS products generally come with the following types of system software.

Streamlined Windows 2000 system

This type of system only retains the most important part of the core network of the WINDOWS2000 SERVER system and can drive the normal operation of NAS products. We can think of it as a "simplified version" of WINDOWS2000.

FreeBSD Embedded System

FreeBSD is a UNIX-like system with excellent performance in network applications.

Linux Embedded Systems

The Linux system is similar to the UNIX operating system, but it has a more user-friendly interface and faster kernel upgrades. It is often used as an embedded control system for electrical appliances and other products.

6. Network Management

Network management refers to the centralized management of network resources by network administrators through network management programs, including configuration management, performance and accounting management, problem management, operation management, and change management. The degree of management supported by a device reflects the manageability and operability of the device.

The general network meets the SNMP MIB I / MIB II statistical management functions. Common network management methods are as follows:

(1) SNMP management technology

(2) RMON management technology

(3) Web-based network management

SNMP is the abbreviation of "Simple Network Management Protocol" in English, which means "Simple Network Management Protocol" in Chinese. SNMP was first proposed by a research team of the Internet Engineering Task Force (IETF) to solve the problem of router management on the Internet.

SNMP is the most commonly used environment management protocol. SNMP is designed to be protocol-independent, so it can be used on IP, IPX, AppleTalk, OSI, and other used transport protocols. SNMP is a series of protocol suites and specifications (see the table below) that provide a way to collect network management information from devices on the network. SNMP also provides a way for devices to report problems and errors to network management workstations.

At present, almost all network equipment manufacturers have implemented support for SNMP. The leading SNMP is a public communication protocol that collects management information from devices on the network. The device manager collects this information and records it in the Management Information Base (MIB). This information reports the characteristics of the device, data throughput, communication overload and errors, etc. MIB has a common format, so SNMP management tools from multiple manufacturers can collect MIB information and present it to the system administrator on the management console.

By embedding SNMP into data communication devices, such as switches or hubs, these devices can be managed from a central station and information can be viewed graphically. Many management applications currently available can usually run under most currently used operating systems, such as Windows 3.11, Windows 95, Windows NT, and different versions of UNIX.

A managed device has a management agent, which is responsible for requesting information and actions from the management station. The agent can also provide the management station with information provided by the station through traps. Therefore, some key network devices (such as hubs, routers, switches, etc.) provide this management agent, also known as SNMP agent, so that they can be managed through the SNMP management station.

7. Network Protocol

Network protocols are the rules for transmitting and managing information in networks (including the Internet). Just as people need to follow certain rules when communicating with each other, computers need to follow certain rules when communicating with each other. These rules are called network protocols.

A computer can communicate with other computers on the network only if it complies with the network protocol. Network protocols are usually divided into several levels, and each level performs its own independent functions. The two parties can communicate with each other only at the common level. Common protocols include: TCP/IP protocol, IPX/SPX protocol, NetBEUI protocol, etc. IPX/SPX is more commonly used in local area networks. If users access the Internet, they must add TCP/IP protocol to the network protocol.

TCP/IP is the abbreviation of "transmission control protocol/internet protocol". TCP/IP (transmission control protocol/internet protocol) is a network communication protocol that regulates all communication devices on the network, especially the data exchange format and transmission method between one host and another. TCP/IP is the basic protocol of the INTERNET and a standard method for computer data packaging and addressing. In data transmission, it can be figuratively understood as having two envelopes. TCP and IP are like envelopes. The information to be transmitted is divided into several segments. Each segment is stuffed into a TCP envelope, and the information with the segment number is recorded on the envelope. Then the TCP envelope is stuffed into the IP envelope and sent to the Internet. At the receiving end, a TCP software package collects the envelope, extracts the data, restores it to the order before sending, and verifies it. If an error is found, TCP will request retransmission. Therefore, TCP/IP can transmit data almost error-free in the INTERNET. For ordinary users, it is not necessary to understand the entire structure of the network protocol. You only need to understand the IP address format to communicate with people all over the world.

IPX/SPX is based on Xerox's XEROX'S Network System (XNS) protocol, while SPX is based on Xerox's XEROX'S SPP (Sequenced Packet Protocol) protocol. They are both high-speed protocols developed by Novell for use in local area networks. A significant difference between it and TCP/IP is that it does not use IP addresses, but uses the physical address of the network card, namely the (MAC) address. In actual use, it basically does not require any settings, and can be used after installation. Because it played a huge role in the early days of network popularization, it has been supported by many manufacturers, including Microsoft, and many software and hardware still support this protocol.

NetBEUI is NetBios Enhanced User Interface. It is an enhanced version of NetBIOS protocol and has been adopted by many operating systems, such as Windows for Workgroup, Win 9x series, Windows NT, etc. The NETBEUI protocol is very useful in many situations and is the default protocol for operating systems before WINDOWS98. In short, the NetBEUI protocol is a compact and efficient broadcast protocol with high communication efficiency. It does not require any settings after installation and is particularly suitable for transmitting data in "Network Neighborhood". Therefore, it is recommended that in addition to the TCP/IP protocol, the computers in the LAN should also install the NetBEUI protocol. Another point to note is that if a WINDOWS98 machine with only the TCP/IP protocol installed wants to join the WINNT domain, the NetBEUI protocol must also be installed.

8. Network File Protocol

The network file system is a network-based distributed file system. The nodes of its file system tree can exist on different networked computers or even different system platforms, and can be used to provide cross-platform information storage and sharing.

The two most important network file systems today are NFS (Network File System) proposed by Sun and CIFS (Common Internet File System) proposed by Microsoft, EMC and NetApp. The former is mainly used on various Unix platforms, while the latter is mainly used on Windows platforms. The file sharing method of "Network Neighborhood" that we are familiar with is based on the CIFS system. Other well-known network file systems include NCP (Network Control Protocol) of Novell, AFP of Apple, and Coda of Carnegie Mellon University. One of the main functions of NAS is to provide storage services through various network file systems.

9. Network backup software

At present, the software products that can complete network data backup management in the field of data storage mainly include Legato's NetWorker, IBM's Tivoli, Veritas' NetBackup, etc. In addition, some operating systems, such as Unix's tar/cpio, Windows 2000/NT's Windows Backup, and Netware's Sbackup, can also be used as NAS backup software.

NetBackup

NetBackup is a backup software launched by Veritas for medium and large storage systems, which can widely support various open platforms. In addition, the company has also launched Backup Exec, a backup software suitable for low-end.

NetWorker

NetWorker is a backup software launched by Legato. It is suitable for large and complex network environments, has various advanced backup technology mechanisms, and widely supports various open system platforms. It is worth mentioning that the Cellestra technology in NetWorker is the first to implement the idea of ​​Serverless Backup in products.

IBM Tivoli

IBM Tivoli is a backup software launched by IBM. Compared with Veritas' NetBackup and Legato's NetWorker, Tivoli Storage Manager is more suitable for system platforms based on IBM mainframes. Its powerful network backup function can meet the backup needs of large-scale massive storage systems.

In addition, CA's original backup software ARCServe has a wide influence in the low-end market. Its new generation backup product, BrightStor, is positioned directly for the mid-to-high-end market and also has good performance.

When purchasing backup software, you should choose the right product based on different user needs. The ideal network backup software system should have the following functions:

Centralized management

The network storage backup management system manages the data of the entire network. With the help of centralized management tools, system administrators can manage the backup strategy of the entire network in a unified manner. The backup server can monitor the backup jobs of all machines, modify the backup strategy, and browse all directories in real time. All data can be backed up to any tape library connected to the backup server or application server.

Fully automatic backup

The backup software system should be able to define the data that needs to be backed up according to the actual needs of the user, and then set the backup schedule as needed in a graphical interface. The backup system will automatically start the backup job without manual intervention. This automatic backup job is customizable, including one-time backup jobs, certain days of the week, and the first few days of the month. After setting the plan, the backup job will be automatically carried out according to the plan.

Database backup and recovery

In many people's minds, database and file are still the same concept. Of course, if your database system is based on the file system, you can use the file backup method to back up the database. But now, the database system has become quite complex and large, and it is no longer applicable to use the file backup method to back up the database. Whether the required data can be extracted from the huge database file for backup is one of the signs of whether the network backup system is advanced.

Online indexing

The backup system should establish an online index in the server for daily backup. When the user needs to restore, he only needs to click the file or data that needs to be restored in the online index, and the system will automatically restore the file.

Archive Management

Users can effectively archive all data regularly by project and time. Providing a unified Open Tape Format data storage format ensures that all application data is permanently stored in a unified data format, ensuring the permanent availability of data.

Effective media management

The backup system automatically adds an electronic label to each tape used for backup, and provides a label identification function in the software. If the label on the outside of the tape falls off, just execute this function to quickly know the contents of the tape.

Meeting the increasing demands of the system

The backup software must be able to support multi-platform systems. When other application servers are connected to the network, for the network storage management system, it only needs to install the client software that supports this server to back up the data to the tape library or CD library.

10. Website browser support

Web browser support refers to whether the NAS product can be managed through the WEB (WWW, commonly known as the Internet) and the type of browser used for management. Most NAS products support WEB management, which is convenient for management. Users can easily manage NAS devices anywhere as long as they can access the Internet.

Currently, the commonly used browsers supported by NAS products include Microsoft's IE (Internet Explorer) browser and Netscape's Netscape browser.

11. Network Services

Network services refer to the services that the NAS product system can provide when it is running. Typical network services include DHCP, DNS, FTP, Telnet, WINS, SMTP, etc.

DHCP

The full name of DHCP is "Dynamic Host Configuration Protocol". In a network using DHCP, the user's computer can obtain Internet access parameters from the DHCP server, and can access the Internet without any manual configuration. Generally, the DHCP server will try to keep each computer using the same IP address to access the Internet. If a computer has not been online for a long time or is configured to use a static address to access the Internet, the DHCP server will assign this address to other computers.

WINS

WINS is the abbreviation of "Windows Internet Name Service", which means Windows Internet Naming Service in Chinese. WINS server is mainly used for NetBIOS name (computer name) service. It processes NetBIOS computer name (Computer Name), so it is also called NetBIOS name server (NBNS, NetBIOS Name Server). WINS server can register the computer name, IP address, DNS domain name and other data of WINS-enabled workstation (hereinafter referred to as "WINS workstation"), and it can provide these data to the workstation when the workstation queries the name.

DNS

DNS, Domain Name System or Domain Name Service. The Domain Name System assigns domain name addresses and IP addresses to hosts on the Internet. When a user uses a domain name address, the system will automatically convert the domain name address into an IP address. Domain Name Service is an Internet tool that runs the Domain Name System. The server that executes the Domain Name Service is called a DNS server, and the DNS server is used to answer queries for the Domain Name Service.

FTP

FTP (File Transfer Protocol) is one of the traditional services of the Internet. FTP allows users to transfer files between two networked computers. It is the main method of transferring files on the Internet. Using anonymous FTP, users can access the rich resources of the Internet for free. In addition, FTP also provides login, directory query, file operation and other session control functions.

SMTP

SMTP (Simple Mail Transfer Protocol) is a set of rules for sending mail from source address to destination address, which controls the transfer method of mail. SMTP protocol belongs to TCP/IP protocol family, which helps each computer find the next destination when sending or transferring mail. Through the server specified by SMTP protocol, we can send E-mail to the recipient's server, and the whole process only takes a few minutes. SMTP server is a sending mail server that follows SMTP protocol, which is used to send or transfer your sent emails.

Telnet

Sometimes we need to run some large programs, but our PC does not have the necessary configuration to run the program. In this case, we can connect to a powerful computer through the network and simulate our PC as the terminal of that computer to run the program on that computer. This method of using the network to remotely log in to other computers and remotely control the program in a virtual terminal is called TELNET. With the development of computer hardware, TELNET is no longer very common among general network users, but it is still a powerful assistant for network administrators.

12. Cybersecurity

Network security means that the hardware, software and data of the network system are protected from damage, change or leakage due to accidental or malicious reasons, and the system runs continuously, reliably and normally without interruption of network services.

Network security actually consists of two parts: network security and host system security. Network security is mainly achieved by setting up firewalls. You can also consider setting up some packet filtering methods on the router to prevent attacks from hackers on the Internet. As for system security, you need to modify related system files according to different operating systems, and reasonably set user permissions and file attributes.

The network security of NAS products should have the following four characteristics:

Confidentiality: The property of information not to be disclosed to, or made available to, unauthorized users, entities, or processes.

Integrity: The property of data that cannot be altered without authorization. That is, information remains unchanged during storage or transmission.

The characteristics of not being changed, destroyed or lost.

Availability: The property of being accessible to authorized entities and used as needed. That is, whether the required information can be accessed when needed.

For example, denial of service in a network environment, disruption of normal operation of the network and related systems, etc. are all attacks on availability;

Controllability: The ability to control the dissemination and content of information.

13. NAS

NAS is the abbreviation of "Network Attached Storage" in English, which means "network attached storage" in Chinese. Simply speaking, it is a device connected to the network and has data storage function, so it is also called "network storage" or "network disk array".

Structurally, NAS is a streamlined computer with a single function. Therefore, its architecture is not as complex as that of a personal computer. It looks like a home appliance, requiring only a power supply and simple control buttons. The structural diagram is as follows:

NAS is a professional network file storage and file backup device. It is based on LAN (local area network), communicates according to the TCP/IP protocol, and transmits data in the form of file I/O (input/output). In the LAN environment, NAS can fully realize data-level sharing between heterogeneous platforms, such as NT, UNIX and other platforms.

A NAS system includes a processor, a file service management module and multiple hard disk drives (for data storage). NAS can be used in any network environment. The main server and the client can easily access files in any format on the NAS, including SMB format (Windows), NFS format (Unix, Linux) and CIFS (Common Internet File System) format, etc. The typical NAS network structure is shown in the figure below:

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