Differences between San, NAS, and DAS Architectures

Source: Internet
Author: User
With Technology Development and extensive Application The storage technology has been applied in the industry and various application fields. Professional People's attention. Data The rapid growth of traffic is Enterprise New problems and requirements are raised, how to ensure data consistency, security and reliability, and how to centralize different data Management , How to implement Network How to achieve different Host Data access and protection. All of these call for the emergence of new network storage technologies and products.

SanAndNASThe emergence of technologies and products not only expands the development of the NetworkSpaceMore importantly, they combine network technologies with emerging storage fields and play an important role in the development of the IT industry.

San and NAS are often regarded as two competing technologies. In fact, they can complement each other well to provide access to different types of data. San for massive data block-oriented data transmission, while NAS providesFileLevel Data access function.

These two technologies not only meet the needs of flexible storage access, but also San and NAS are based on open, industry-standard network protocols: used for SanOptical FiberThe channel protocol and the network protocol for NAS (such as TCP/IP ). San is widely used and can provideDeviceNAS is generally limited to applications that access file-level data. Without considering the differences between them, San and NAS play an important role in today's enterprise-level storage, compared with traditionalServerConnected storage has more advantages.

San and NASServiceDevice connection storage is a powerful supplement and alternative. As a result, enterprise users gradually recognize its many advantages, including improved flexibility, more convenient storage deployment, and lower total cost of ownership. Although San and NAS technologies can provide competitive advantages, they are designed for specific environments and applications.


Key features of San

As a network infrastructure, San is designed to provide a flexible, high-performance, and highly scalable storage environment. San achieves this goal by connecting servers and storage devices (such as disk storage systems and tape libraries.

High-performance fiber channel switches and fiber channel network protocols ensure that the device connection is reliable and effective. These connections are based on local optical fiber or SCSI (via SCSI-to-Fiber Channel converter or gateway. One or more fibre channel switches are interconnected between host servers and storage devices in the form of a network topology (SAN architecture.

San is ideal for the following applications because it is optimized to transmit large volumes of data between servers and storage devices:

Key task database applications, with predictable response times, availability, and scalability as the basic elements.
Centralized storage and backup, in which performance, data consistency and reliability can ensure the security of key enterprise data.
High Availability and Failover environments ensure lower costs and higher application levels.
Scalable Storage Virtualization separates storage from direct host connections and ensures dynamic storage partitions.
The improved Disaster Tolerance feature provides fiber channel performance and a scalable distance (up to 150 km) between host servers and Their connected devices ).
Main strengths of San

Facing the rapid growth of data storage requirements, large enterprises and service providers are gradually choosing San as the network infrastructure, because San has excellent scalability. In fact, San has more significant advantages than traditional storage architecture. For example, traditional server connection storage is usually difficult to update or centrally manage. Each server must be shut down to add and configure new storage. In comparison, SAN does not have to go down or interrupt connections with servers to increase storage. San can also centrally manage data, reducing the total cost of ownership.

Using Fiber Channel Technology, San can effectively transmit data blocks. San provides an effective method for data backup by transferring massive data blocks between storage and servers. Therefore, the network bandwidth traditionally used for data backup can be saved for other applications.

The open and industry-standard fiber channel technology also makes san very flexible. San overcomes the limitations of traditional cables connected to SCSI, greatly expanding the distance between servers and storage, thus increasing the possibility of more connections. The improved scalability also simplifies the deployment and upgrade of servers and protects the investment of original hardware devices.

In addition, San can better control the storage network environment and meet the performance and availability requirements of transaction-based systems. San uses high-reliability and high-performance fiber channel protocols to meet such requirements.

Another strength of San is its ability to transmit data blocks to enterprise-level data-intensive applications. In the process of data transmission, San processes less cost on communication nodes (especially servers) because data is divided into smaller data blocks during transmission. Therefore, the fiber channel San is very effective when transmitting big data blocks, which makes the Fiber Channel Protocol very suitable for storage-intensive environments.

Today, San is gradually integrated with the NAS environment to provide high-performance massive storage for NAS devices. In fact, many San services are currently used in the background of NAS devices to meet storage scalability and backup requirements.


Benefits of San

One benefit of San is that it greatly improves the reliability and scalability of enterprise data backup and recovery operations. San-based operations can significantly reduce backup and recovery time, while reducing the amount of information flowing on the enterprise network.

By expanding san to the Metro infrastructure, San can also be seamlessly connected to remote devices to improve disaster tolerance capabilities. San deploy man infrastructure to increase the distance between San devices, which can reach 150 kilometers, and will hardly reduce performance. Enterprises can use this to improve disaster tolerance by deploying key task applications and remote data replication for key application servers. Remote Management is required to back up and restore devices.

In addition, transaction-based database applications have benefited a lot from San deployment. It can seamlessly increase the storage capability to reduce the data backup time.

San Problems

In the past two years, the concept of San has become increasingly popular. San can replace the server-based storage mode and provide better performance. However, to date, interoperability is still a major problem in the implementation process. San itself lacks standards, especially in terms of management. Although the fiber channel technology standards do exist, vendors have different interpretations. Therefore, the interoperability problem is like a sandstorm.

Some San vendors use organizations such as snia to develop standards. Some vendors have begun to invest heavily in the Construction of interoperability laboratories and conduct tests before launching San. Another way is to outsource San. San vendors have made progress in solving interoperability issues. However, experts still recommend that you use outsourcing instead of building your own San.


Key features of NAS

A nas solution is usually configured as a file service device. A workstation or server uses network protocols (such as TCP/IP) and applications.Program(Such as network file system NFS or general Internet File System CIFS) for file access. Most NAS connections are performed between workstation clients and NAS file sharing devices. These connections depend on the enterprise's network infrastructure for normal operation.

To improve system performance and uninterrupted user access, NAS uses specialized operating systems for network file access. These operating systems support both standard file access, the network protocol is also supported.

NAS makes File Access faster and increases the file storage capacity to the infrastructure. Because NAS focuses on the implementation of file services rather than the actual file system, NAS devices are often self-contained and easy to deploy.

Data transmission is primarily performed between the NAS device and the client. Today, a large amount of data transmitted over the LAN/WAN is divided into many small data blocks. The processing process of transmission takes up processor resources to interrupt and re-access the data stream. If data packet processing occupies too many processor resources, applications running on the same server will be affected. Network Congestion affects the performance of NAs, so one of its performance limitations is the ability to transmit data over the network.

The scalability of NAS storage is also limited by the device size. It is very easy to add another device, but it is not easy to access the content in the network environment just like accessing data on one machine, because NAS devices often have unique network identifiers. Due to these limitations, data backup in the NAS environment is not centralized, so it is limited to using direct connection devices (such as dedicated tape drives or tape libraries) or network-based strategies. In this policy, data on the device is backed up through an enterprise or a dedicated LAN.

Differences between NAS and Das

As a new storage technology, NAS has the advantages that traditional direct connection methods cannot match. Table 1 makes a simple comparison between the two methods.

Table 1 Comparison Between NAS and Das

Network attached storage (NAS)
Network file access can be achieved through centralized management of the file system.
Users can share the file system and view the shared data.
Professional file servers are combined with storage technology to provide high-reliability data for network access.
Direct connection to storage (DAS)
Only the connected host can be used for access.
Each host manages its own file system, but it cannot share data with other hosts.
You can only rely on the storage device itself to provide high-reliability data for the host.

Technical Features of NAS

NAS provides an efficient and cost-effective solution for enterprise environments that access and share large volumes of file system data. Data integration reduces management requirements and overhead, while centralized network file servers and storage environments-including hardware and software-ensure reliable data access and high data availability. NAS provides a powerful integrated mechanism.

NAS technology can meet specific user needs. For example, when some enterprises need to cope with the problem of rapid data growth, or solve the system restrictions caused by independent working environments, they can adopt the next-generation NAS technology, the centralized network file access mechanism and sharing mechanism are used to solve these problems, so as to reduce system management costs and improve data backup and recovery functions.


Main strengths of NAS

NAS is applicable to users who need to transmit file data to multiple clients over the network. NAS devices can play a good role in environments where data must be transmitted over long distances.

In addition, NAS devices are very easy to deploy-Nas hosts, clients, and other devices can be widely distributed across the entire enterprise network environment. After proper configuration, NAS can provide reliable file level data integration, because file locking is handled by the device itself. Despite its ease of deployment, enterprises still need to ensure that appropriate file security levels are provided during the configuration of NAS devices.

Benefits of NAS

NAS is used in efficient file sharing tasks, such as NFS in UNIX and CIFS in Windows NT. Network-based file-level locking provides advanced concurrent access protection. NAS devices can be optimized to provide file-level protection to send file information to multiple clients.

In some cases, enterprises can deploy NAS solutions for database applications. These situations are generally limited to the following applications: a large amount of data access is read-only, the database is small, the logical volume to be accessed is small, and the required performance is not high. In these cases, the NAS solution helps reduce your total cost of ownership.

Two complementary technologies

Although there are differences between them, San and NAS are two complementary storage technologies. For example, San performs well in data block transmission and scalability, and can effectively manage devices. Enterprises can benefit from applying San to key task applications, centralized storage, Backup recovery, and high availability computing.

Compared with San, NAS supports file sharing among multiple peer-to-peer clients. NAS clients can access shared files anywhere in the enterprise. Because there are few logical volumes for file access in the NAS environment and the response time requirement is not high, the performance and distance requirements are relatively low.

Table 2 Comparison of key San and NAS features

Protocol: Fiber Channel-to-SCSI TCP/IP
Application * key tasks, transaction-based database application processing * file sharing in NFS and CIFS
* Centralized data backup * long-distance small data block transmission
* Disaster recovery * limited read-only Database Access
* Centralized storage
Advantage * High Availability * limited distance
* Data Transmission reliability * simplifies the shared capacity of additional files
* Reducing Network Traffic * easy deployment and management
* Flexible configuration
* High Performance
* High scalability
* Centralized Management

many of the original differences between NAS and San began to disappear. For example, NAS devices gradually adopt San to solve problems related to storage expansion and Backup recovery. Although these two technologies are similar, NAS cannot provide comprehensive commercial advantages brought about by San. However, compared with traditional server attached storage, both San and NAS technologies can reduce users' total cost of ownership and provide better ROI.

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