What are the three implementation methods of storage virtualization?

The three ways to implement storage virtualization are: 1. Host-based virtual storage, relying on agents or management software; 2. Storage device-based virtualization, relying on storage modules that provide related functions; 3. , Network-based virtual storage can be divided into interconnected device-based virtualization and router-based virtualization.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

The most popular understanding of storage virtualization is the abstract representation of storage hardware resources. According to virtualization objects, there are three main ways to implement virtualized storage.

Host-based virtual storage

Host-based virtual storage relies on agents or management software, which are installed on one or more hosts to implement storage virtualization Control and management. Since the control software runs on the host, this will take up the host's processing time. Therefore, this method has poor scalability and its actual performance is not very good. The host-based approach also has the potential to impact system stability and security by potentially allowing inadvertent unauthorized access to protected data.

This method requires the installation of appropriate control software on the host, so the failure of one host may affect the integrity of data in the entire SAN system. Software-controlled storage virtualization may also bring unnecessary interoperability overhead due to differences in software and hardware from different storage vendors, so this method is also less flexible. However, because it does not require any additional hardware, the host-based virtualization approach is the easiest to implement and has the lowest equipment costs. Suppliers using this method tend to become software vendors in the storage management field, and currently have mature software products. These software can provide easy-to-use graphical interfaces, easily used for SAN management and virtualization, and have good load balancing mechanisms in hosts and small SAN structures. In this sense, host-based storage virtualization is a cost-effective method.

Storage device-based virtualization

The storage device-based storage virtualization method relies on storage modules that provide related functions. Without third-party virtualization software, storage-based virtualization often provides an incomplete storage virtualization solution. For SAN storage systems containing multi-vendor storage devices, this method does not work very well. Functional modules that rely on storage vendors will exclude the use of JBODS (Just a Bunch of Disks, simple hard disk groups) and simple storage devices in the system, because these devices do not provide storage virtualization functions.

Of course, using this approach means ultimately locking in a single storage provider. A storage-based virtualization approach also has some advantages: it is easier to implement in a storage system, easier to coordinate with a specific storage vendor's equipment, so it is easier to manage, and it is transparent to users or administrators. . However, we must note that the lack of adequate software support makes the solution more difficult to customize and monitor.

Network-based virtual storage

1) Virtualization based on interconnected devices

If the method based on interconnected devices is symmetrical, then the control information and data travel on the same channel; if it is asymmetric, control information and data travel on different paths. In a symmetrical manner, interconnected devices may become a bottleneck, but multiple device management and load balancing mechanisms can alleviate bottleneck conflicts. At the same time, in a multi-device management environment, when a device fails, it is easier to support the server to take over the fault. However, this creates multiple SAN islands because one device only controls the storage system to which it is connected. Asymmetric virtual storage is more scalable than symmetric because the paths for data and control information are separated.

Internet-based virtualization methods can run on dedicated servers using standard operating systems such as Windows, SunSolaris, Linux or vendor-provided operating systems. This approach runs on a standard operating system and has many of the advantages of a host-based approach - ease of use and cheap equipment. Many device-based virtualization providers also provide additional functional modules to improve the overall performance of the system. They can obtain better performance and more complete functions than standard operating systems, but require higher hardware costs. However, the device-based approach also inherits some of the drawbacks of the host-based virtualization approach, as it still requires an agent software or host-based adapter running on the host, and any host failure or inappropriate host configuration may lead to access to unprotected data. At the same time, interoperability among heterogeneous operating systems remains an issue.

2) Router-based virtualization

The router-based approach is to implement the storage virtualization function on the router firmware. Vendors also often provide add-on software that runs on the host to further enhance storage management capabilities. In this method, a router is placed in the data channel from each host to the storage network to intercept any command from the host to the storage system in the network. Since the router potentially serves every host, most control modules exist in the router's firmware, which results in better performance and better results than host-based and most connected device-based approaches. By not relying on a proxy server running on each host, this approach provides better security than host-based or device-based approaches.

When the router connecting the host to the storage network fails, the data on the host may still be inaccessible. However, only hosts connected to the failed router will be affected; other hosts can still access the storage system through other routers. Router redundancy can support dynamic multipathing, which also provides a solution to the above failure problem. Since routers often serve as bridges for protocol translation, a router-based approach can also provide interoperability between heterogeneous operating systems and multi-vendor storage environments.

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