Virtualization's new voice: virtualization plays an important role in an overall data management strategy.

Virtualization seems to have made a comeback of sorts lately. Only four short years ago, "storage virtualization" was viewed as the ultimate solution for managing storage. But as a core technology in and of itself, the buzz quickly evaporated. The downfall of virtualization seemed just as fast as its ascent in the storage industry.

But listen carefully as whispers of virtualization are getting louder. The current reality is that when spoken in conjunction with enabling storage services such as replication, mirroring and rapid data recovery, virtualization has a new voice and serves as a key enabling factor for the proliferation of data services in an environment with a heterogeneous operating system and multiple storage devices. Virtualization can play a vital role in overall data management strategy. This article will examine the factors behind the renewed attention being paid to the virtualization story and why that attention is justified when used in conjunction with storage services.

Virtualization is not all it's cracked up to be, without the proper framework. Clever "virtualization" technology masks the differences in storage hardware and presents a unified way to interact with disk/tape devices from different manufacturers.

The true value of virtualization can only be realized within a full-featured storage solution that leverages a customer's current IT infrastructure and provides not just virtualization but top performance (fast data storage and access), ease of use, unified SAN and NAS management, virtualization across cabinets (not just within one storage cabinet), and seamless support of heterogeneous storage environments. For a virtualization solution to make business sense, it must offer total freedom of choice in device vendors, interfaces, connectivity, platforms and protocols.

But where does it make sense to virtualize? Disk-level virtualization is limited to specific vendor devices and, at the application host-level, it can be seen as a synonym for volume management--host-based, operating system-specific, and with a point of control on every single machine on the network. Ideally, storage virtualization has no operating system specificity and can be managed centrally, rather than from each host in the environment. A true virtualization model cuts across vendor barriers.

The most effective location for virtualization is in the storage network. By interjecting a layer of intelligence between servers and storage, network-based virtualization offers the most freedom from operating system constraints and vendor-specific storage devices. It is also completely centralized, as the intelligent "nodes" can be managed from a single point of view.

A well-architected "network-based" storage infrastructure software should be able to virtualize the disk and/or tape storage from multiple vendors, provision the virtual disk to the host-attached Fibre Channel/iSCSI/CIFS/ NFS network while provisioning the virtual tape to hosts attached to the Fibre Channel and iSCSI networks, and associate mission-critical storage services (replication, snapshot, backup, HSM, etc.) to the logical disk and/or tape. It should be so seamless that an ISV developing an application in Windows does not have to worry about the underlying storage devices or protocols.

As another example: With virtualization, good RAID software should present a logical disk (RAID-0 or 1 or 5, etc.) to the upper layer, and allow the user to employ the SCSI/Fibre Channel/ATA/SATA disk from any manufacturer; smart RAID software should enable the application/administrator to expand or shrink the logical disk on-the-fly, and be able to perform snapshot, replication, backup, etc., in real time without affecting the upper layer application; and a network-based, intelligent RAID software should be able to offer "logical disk" but also "logical tape" and allow the application host to access the logical disk through the Fibre Channel/ iSCSI/CIFS/NFS network and the logical tape through the Fibre Channel/iSCSI network.

Significant Benefits in Data Management

Built on a solid foundation, virtualization offers significant benefits in data management. Implemented effectively, virtualization offers a layer of abstraction above the physical layer of disks and spindles. The issue with the physical layer is that it varies from vendor to vendor, and even between device models from the same vendor, making storage provisioning quite a challenge. A virtualization solution unifies everything (RAID and JBOD, iSCSI, SCSI and Fibre Channel) and makes it all look the same. In short, it provides a utility model for storage. Disk space is carved out of a pool and assigned to servers without any need to physically touch the servers.

What storage virtualization brings to the table is a way of incorporating storage services into the network, without any reliance on operating system or storage-specific tools. This is the true business benefit, and what many end users are beginning to realize.

As an enabler of services addressing the storage pain of IT administrators, virtualization now speaks a language IT administrators can understand.

Supports Remote Data Access, Backup, Mirroring, Replication

A value-added storage virtualization solution enables IT administrators to create backups and mirror space on disks configured virtually anywhere in a system or across IP networks. It enables disaster recovery services such as replication of data across IP to a remote site, and rapid data and system recovery services such as bare metal recovery and online/nearline disk-based backups. This not only eases administration for the local SAN managers--since they can remain at their central location--but also benefits the entire enterprise, since it makes critical data inexpensively available outside a geographically local area. And, of course, it ensures that a business can continue operating in the event of damage or loss of a primary data set.

Ensures Business Continuity

Virtualization allows for rapid storage growth and reconfiguration, without the downtime that expansion usually entails. This is a vital advantage for today's enterprises, which are increasingly running in fast-paced 24x7 mode. Volumes of storage can be allocated to application servers on the fly, without interrupting operation.

In order to truly assure business continuity, an advanced virtualization solution should make it possible to safeguard against all possible single points of failure on storage devices, server hardware, networking hardware, and even complete site failure due to disaster. In an age when businesses can't operate without access to their data, less downtime and disaster protection translate into higher returns for enterprises.

To guard against failure of storage systems, the solution should enable mirroring of virtual disks, and not just within cabinets but also across cabinets--even if they are made by different vendors--and across any distance. To defend against server hardware failure, an advanced virtualization solution should support high availability configurations, enabling full redundancy throughout the entire data path so that there is no single point of failure. To protect against site failure from a variety of disasters, the solution should support remote replication of virtual disks to keep an extra set of data off site.

Facilitates Fast Data Access

For all intents and purposes, a virtualized volume mimics an actual physical device. However, a superior virtualization solution succeeds at generating virtual disks that far surpass their physical cousins in speed and functionality. In this way, virtualization can significantly improve the performance of a storage network. This is crucial, as speedy access to data is a critical benchmark for modern enterprises whose customers want products fast and demand answers now.

Virtualization, in combination with other functionalities, can be particularly beneficial when performing tape backups. Virtual volumes can be staged on disks and later backed up to tapes, thus offloading I/O and processing cycles from the application server. For example, by leveraging IPStor software's delta-based snapshot techniques and/or virtual tape technology, truly LAN-free/server-less/windowless backups become a reality.

Enables Interoperability With Storage Hardware

Another key benefit of virtualization is interoperability. Masking the complexity of various vendors' storage solutions ideally creates an environment where every disk subsystem appears the same to the host server. The actual disk subsystem behind the virtual image can be anything. In a virtualized storage architecture, enterprises can purchase their storage knowing that it can just be plugged in to start working, without complex and time consuming configurations--or a total lack of interoperability--thus significantly decreasing their investment and increasing financial return.

Virtualization can keep enterprises immune to becoming captive to a specific vendor or proprietary technology and the higher initial and recurring costs that this tends to involve. Because virtualized storage is agnostic with respect to vendors and technology, IT administrators are given the freedom to choose the best solution for their organization. This also encourages healthy competition in the storage appliance industry, bringing added benefits over time in the form of technological advances and fine-tunings.

Reduces Managerial and Administrative Overhead

A storage infrastructure that employs virtualization is considerably easier for IT administrators to manage, saving them a great deal of time and effort. Instead of expending huge chunks of time on hardware modifications--physically attaching, moving around and configuring devices--they can effortlessly assign, unassign, or reassign virtual volumes from a central location. Not only does this leave administrators with more time to do all of the other things on their plates, it saves enterprises resources, as fewer IT staff are needed to manage much larger amounts of storage.

Easy, Effective Management of Storage Network/Devices

A virtualized approach makes it much easier to add and maintain storage devices. An advanced solution applies an intuitive Graphical User Interface (GUI) to visualize storage and then assign and manipulate it as needed. Furthermore, dynamic modification of access permissions to virtual volumes can be performed on the fly. Online and transparent migration of storage devices allows maintenance and upgrade of storage devices without shutting down applications.

While, in the past, virtualization was more heat than substance, things are settling down now. The argument for storage virtualization is now becoming too compelling for IT administrators to ignore, as they are now hearing the value proposition of open storage services platforms.

Gabriel Lopez is product manager at FalconStor Software, Inc. (Melville. NY)

www.falconstor.com