Development status and future trend of virtualization storage technology (I.)

Virtualization is an effective means to implement simple management of logical environment. Through virtualization, users will get rid of the complexity of the underlying physical environment, make full use of storage space based on heterogeneous platform, and realize the effective planning of resources on the basis of openness. Virtualization automates the configuration of storage devices and their space, enabling users to use all of the physically dispersed storage resources within a domain to manage unpredictable events across regions, such as business discontinuities, adjustment to capacity requirements, and employee changes. Regardless of the location, size, type, and manufacturer of the storage domain where these storage resources are located, they are managed from a single logical view.

One, "Virtual storage is like a translator"

In a SAN environment, storage virtualization can be based on host, network, and storage devices, like a conference room with speakers and listeners, where the speaker is the host, and the audience is like a storage device, but the speaker and the audience speak different languages and cannot communicate with each other directly. While virtual storage is like a translator, host-based virtual storage is like installing a translator on a speaker; Virtual storage based on storage devices is like installing the translator on every listener; Virtual storage based on the network is like a same-pass device in the conference room. With the translator installed, the speaker and the audience can communicate smoothly, and the translator is installed in different locations to form the virtual storage at different levels.

The virtual storage of these three architectures applies to different environments, host-based virtual storage for host-centric IT environments with fewer hosts or even single hosts; storage-based virtualization for heterogeneous San architectures, more for storage-centric environments, independent of hosts, Its storage device can connect multiple hosts, but the storage device itself cannot be heterogeneous; network-based storage Virtualization is ideal for open storage networks, the open SAN, which is independent of the host and is also independent of storage devices, and is therefore the most flexible. In practice, which is the most effective way to use, the principle is to spend the least energy and financial resources, choose the most suitable one or even two or three combinations to achieve storage virtualization.

Second, the distinction of virtual storage technology

(1) host-based Virtual storage

host-based Virtual storage relies on agents or management software that is installed on one or more hosts to achieve control and management of storage virtualization. Because the control software is running on the host, this will occupy the processing time of the host. Therefore, the extensibility of this method is poor, and the performance of the actual operation is not very good. Host-based methods can also affect system stability and security, because it can lead to inadvertent access to protected data. This approach requires that the appropriate control software be installed on the host, so a failure of one host can affect the integrity of the data throughout the San system. The storage virtualization of software control may also cause unnecessary interoperability overhead due to differences in hardware and software of different storage vendors, so the flexibility of this approach is also poor.

However, because no additional hardware is required, host-based virtualization methods are easiest to implement and have the lowest cost of equipment. Vendors using this approach tend to be software vendors in storage management, and there are already mature software products. These software can provide a user-friendly graphical interface for easy management and virtualization of Sans, with good load-balancing mechanisms in both host and small San architectures. In this sense, host-based storage virtualization is a good cost-effective approach.

(2) Virtualization based on storage devices

Storage-device-based storage virtualization methods rely on enclosures that provide the relevant functionality. Without third-party virtual software, storage based virtualization often provides an incomplete storage virtualization solution. This approach does not work well for SAN storage systems that contain multiple vendor storage devices. Functional modules that depend on the storage vendor will exclude the use of Jbods (Just a Bunch of disks, simple hard disk groups) and simple storage devices in the system because they do not provide storage virtualization functionality. Of course, using this approach means that a single storage vendor will eventually be locked out.

The storage-based virtualization approach also has some advantages: This approach is easier to implement in a storage system and easier to manage with the device of a particular storage vendor, so it is more manageable and transparent to users or managers. However, we must note that because of the lack of sufficient software to support this, it makes the solution more difficult to customzing and monitor.