On the extension of regional storage network (SAN)

Network in the past few years, the dependence of Chinese enterprises on E-commerce Solutions has mentioned an unprecedented level. Mission-critical business data capacity is also growing proportionally, and businesses must store, network, protect, and manage that data.

IDC estimates that China's external storage market has grown by an average of 17.9 a year in recent years, with 2005 market value reaching $830 million trillion.

Many organizations have deployed high-performance storage networks (Sans). These stored data must be backed up. In the past, businesses typically only make local backups. But after the 911 terrorist attacks in the United States, the global atypical pneumonia, the North American Blackout and other accidents, enterprises are aware of disaster recovery and business continuity needs. A 48-hour storage-system outage could bankrupt a data-intensive enterprise, according to research. As a result, the need for Remote Storage network expansion is increasing. In addition, the consolidation of storage resources and data centers, and the outsourcing of storage networks, also drive the need for storage network expansion.

Cost and technical requirements for different applications of storage network expansion

Before exploring storage network expansion scenarios and technologies, understand the cost and technical requirements of storage network extensions for different applications.

Data storage can have multiple recovery strategies that largely determine the time required for recovery and the cost of recovering applications.

Standard recovery and tape backup costs are lower, but it takes a long time to complete the recovery. High-end applications such as disk mirroring and geographic clustering can complete recovery in a very short time, but the cost is relatively high. This is because high-end applications for bandwidth requirements and network transmission latency requirements higher. The following figure shows how different applications relate to recovery time and cost. In considering the recovery strategy of data storage, enterprises depend on the requirements of disaster recovery time and the cost that can be borne.


Different storage network extension applications have different transmission bandwidth requirements and quality of service requirements between storage networks. The following illustration shows their relationship. These transport bandwidth and quality of service requirements determine the required storage network expansion technology.


The choice of storage network extension technology

At present, storage network expansion technology can be broadly divided into four categories: 1 traditional channel Extender, 2 san over WDM, 3 san over IP, and 4 san over SDH.

Traditional Channelextender solutions typically convert storage services to ATM services and then transmit them. This type of equipment produces a high latency, expensive, bulky, difficult to operate, so it is less used in new storage network expansion projects.

SAN over WDM Solutions provide a plurality of transparent channels on a pair of optical fibers, providing the best transmission performance and minimum latency with a full rate transport storage Network service. DWDM Price is higher than the cost,

Limits its scope of application. In recent years, the new San over CWDM (coarse wavelength division multiplexing) solutions, such as the Ciena CN 2600 products, provide the best transmission performance, but also solve the high cost of DWDM, in the area of storage expansion has been widely used.

SAN over IP solutions enable organizations to leverage their existing virtual private network (VPN) or public Internet delivery storage network business. Due to the high latency caused by IP networks, the performance is not guaranteed and can not meet the requirements of many applications in service quality, so it is only suitable for low-end extension applications such as standard recovery and tape backup.

SAN OVERSDH Solutions, which carry storage business to the SDH network, ensure low latency and high performance, and also transmit farther distances (such as 100 km or more).

The following figure shows the solutions that are applicable to different enterprise customers and different extension applications.