Status analysis and future development of SAN switches

The Storage Area Network (SAN) is called the "second network", after years of development, the second network has evolved from a "two-tier" network into a "three-tier" network.

An isolated two-layer network

The storage Area network is a proprietary network designed specifically for large-scale data transfer, which uses Fibre Channel protocols to connect disk arrays, libraries, and associated servers through Fibre Channel hubs and switches, creating a high-speed private network. Therefore, the biggest feature of San is independence, even in the early days, it is physically separated from other networks.

Although Sans provide a high-performance, highly reliable "second network" for large data storage for users, users have long been the backbone of multiple San Islands. Each island may be used to satisfy a user's application. However, as with the information-sharing difficulties caused by direct-attached storage, data between islands of each SAN is equally inaccessible.

In order to eliminate the islands of information, the San was invented to allow data to be shared between servers, and as the San was built, a new island was created. Data sharing between new islands is more difficult, and as users ' demands for data sharing become higher, they want to connect the islands of the SAN.

There are four ways to achieve this, including bare-fiber direct-attached, WDM (wavelength division multiplexing), using SONET (SDH) data transfer technology, and FCIP technology, so several San islands can be set to become a large SAN network.

Multi-island interconnect problem in San from the existing San network technology, four kinds of connections will form a fabric network of multiple points, so that in a fabric network there is a unified network services (such as a unified name server, partition configuration, address space, fabric management, etc.), In a remote connected environment, there are many problems, mainly in the following areas.

The problem with the main switch (Principal switch): In Fibre Channel technology, a fabric network has only one main switch, which allocates domain IDs uniformly, ensuring that the entire fabric has a consistent address space, and when the primary switch fails, will cause the entire fabric to be reconfigured (reconfigure), disrupting application operation. So no matter where the main switch is, the failure can have a fatal effect on the other side.

The problem with the main ISL (inter-switch link, inter-switch link): The links at both ends of the remote connection are generally wired between the switches, and they also assume the transfer of the Switch management information (the primary ISL link), which is very likely to occur when the fault is intermittent, When this main ISL link fails, the reconfigure of the sans of the primary switch and the election of the new master switch can also cause disruption of the application system; It also causes a fabric build process on the San Islands of the main switch, which, if unsuccessful, can also cause disruption of the application system.

The problem of joining or withdrawing a switch: Because multiple endpoints are connected to a fabric network, a domain ID conflict may occur when anyone in the network joins or withdraws a switch from any point in the network, which reconfigure the entire fabric. The same can cause disruption to the application system, even if there is no domain ID conflict, the entire fabric will have a fabric build process, if for some reason this process is unsuccessful, the application system will be interrupted.

Security issues between remote points: security is a prominent issue in a remote-connected San network, because anyone can connect to the entire fabric network from any point in the network, and if the WWN (global name) of other application system HBAs can be emulated, the data will be stolen, if there is any man-made damage, Also causes the entire fabric network to be paralyzed, thus the entire application system will not function properly.

Problems in a multi-point disaster-tolerant environment: if in a multiple-point environment, the various San Islands connected to form a large fabric network, remote ISL link More, there are more problems of remote connectivity, and any San Island, any of the above problems, Can result in instability of fabric networks or disruption of application systems, network security and stability will be a prominent problem in the case of multiple remote connections.

San routers came into being in order to solve all kinds of problems of the above San Islands interconnection, San routing technology emerged. It is possible to use SAN routing technology to connect Fibre Channel fabrics that have hitherto been disconnected and to enable each fabric to maintain its mutual independence. San routing technology brings many benefits to networked storage and disaster-tolerant systems.

San routing technology enables seamless connectivity between San fabrics and does not require any modification of existing fabric parameters when connecting different fabrics, while the access to the router does not affect the I/O being performed. San routers enable resource sharing among fabrics, especially for tape library sharing between fabrics. San routers break the limit of up to 239 Fibre Channel switches within a fabric, making it possible to make a large San network. The use of San routers in disaster-tolerant systems can isolate local and offsite San Fabric, greatly improving data availability and overall reliability and stability of disaster-tolerant systems. Multi-fabric interconnection through the SAN routers ensures the autonomy of the management of the San networks of different departments in the same company, and enhances the freedom of each department's San development.

From the implementation of technology, there are currently two main mainstream technology: one is Fcip (FC over IP), the other is IFCP (Internet Fibre Channel protocol).

"Because San plays a more important role in today's data centers, many organizations are looking for innovative solutions that extend the benefits of their sans to the entire enterprise," said Dr. Sima Cong, director of technology at FCIP Brocade Communications China. To support this effort, the unique Brocade silkworm multi-protocol router can increase the functionality, connectivity, and versatility of today's SAN. "This multi-protocol router is used to support multiple routing services, including the Brocade FC-FC routing service for San connectivity, the Brocade FCIP Tunneling service for extended San distances, and Brocade iSCSI Gateway Services for sharing Fibre Channel storage resources with iSCSI servers.

The FC-FC routing service is one of the services on a multi-protocol router that allows devices in different SAN fabrics to establish communications without merging the fabric into a large san. The Brocade FCIP Tunneling service enables organizations to extend their Fibre Channel sans farther away. The use of the Fcip Tunneling service with the FC-FC routing feature enables two fabrics to remain independent without merging them into one, and allows the creation of any fabric that is connected to any device between all devices.

IFCP According to McDATA company China technology Manager Reitao introduced, the company mainly according to a "Secureconnect" Technology design san router. The Secureconnect San routing technology was pioneered by Nishan system, which was McDATA acquired in 2003. Secureconnect SAN Routing technology provides interoperability-capable e_port connectivity for each local San fibre network, terminating e_port connections at each site. As a result, the construction of optical networks is limited to each location, and the protocol between the fiber switch and the switch does not need to penetrate the entire IP network. If two or more locations are connected by McDATA San routers, each location will still have a separate SAN. Between storage devices and servers, only authorized (partitioned) connections are allowed through the IP network.

As with the third-tier network routing, Secureconnect San routing not only ensures reliable transmission of each SAN interval data, but also avoids the potential risk of the entire storage network being exposed to the application of a complete outage. Users can deploy complex, multiple SAN storage solutions with cost-effective IP network services. In addition to error isolation, the Secureconnect San routing solution simplifies SAN connectivity by reducing address duplication issues. McDATA's Secureconnect San routing technology allows you to use the same domain address assignment on different fibre switches without any routing problems.