Virtualization is an increasingly topical topic in computer industry journals. In some articles, it is said that virtualization will be the next frontier of the computer industry. What is computer virtualization and how can you and your customers benefit?

Virtualization is the method that allows other software or hardware applications to run under the same server. The virtual system and the server system would share the same hardware. Virtualization allows multiple systems to share the same physical computer.

For example, a company may invest in a computer system with high processing power and memory, and then, using virtualization, a single administrator may have three or four operating systems running on that computer (depending on the processing power of the computer and the requirements of the operating system).

Only hardware savings could justify your or your customers’ attention to this exciting new technology.

Virtualization doesn’t stop with operating systems; you can also have virtual SAN applications and storage reservoirs. Among these virtualization concepts, the term ‘Virtual Tape Library’ or ‘VTL’ can be explained by presenting storage components such as hard drives and tape hardware.

VTL technology provides a high percentage return on investment, offers easy installation within an existing environment, and facilitates faster data restorations. In addition, VTL does not mean the end of the investment that has been made in tape machines or physical libraries. The backup system architecture can still group data to a physical tape for off-site storage.

In summary, VTL uses hardware and software solutions to redirect backup data that would have been sent to the tape library to a large RAID array. The backup software is able to do this (by means of hardware and software) by reorganizing the RAID array as a tape drive.

Traditional backup options such as full, differential, incremental and snapshot schemes still work the same way on a VTL. Essentially, the backup scheme before the implementation of the VTL will still be available after installation.

Storage concepts of a virtual tape library

VTL storage concepts focus on grouping data from backups to a RAID 0 to RAID 5 configuration. There are several advantages in grouping the data to a disk array first of all; the main thing being the speed.

Tests have shown that the transmission processing capacity is greatly increased. The reason for this is that transmission to magnetic tape is eliminated. In addition, retrieval of archived data is also much faster as there is no obstacle caused by rewinding and advancing operations or cataloguing files and tape sessions.

The storage of a VTL system can start in the range of half terabyte and goes up to hundreds of terabytes according to your needs. The storage can be in the form of high performance ‘Fibre Channel’ or ISCSI systems. On the other hand, SATA (Serial ATA) and PATA (Parallel ATA) systems are available and usually cheaper. All of these storage systems are a good choice for VTL installations.

VTL software and hardware also support multitape virtual libraries. Historically, in environments that use a physical tape machine system employing only one physical tape machine installation it was observed that there was a lot of data flowing into that single device.

To resolve this data movement issue, IT administrators added multiple tape machines, large tape libraries that employ many tape machines, to share the workload and maintain the balance of data movement.

VTL installations offer the same multiplicity of backups running at the same time, which means you can spread the archiving process over a larger number of data areas. However, despite virtualization, it will still be physically stored in the RAID storage array.

For IT environments that have specific policies regarding off-site data storage, almost all VTL systems now support a physical tape library that is connected to the VTL, allowing the consistent flow of archived data to be ‘re-archived’ on a physical tape – a backup of itself.

This helps to ensure doubly that users’ files are being protected. The secondary file is placed on a schedule where tapes can be stored or recycled.

Some organizations have produced an installation of VTL on a WAN scale. In theory, this allows organizations to host a remote disaster recovery website as little as 50 miles away. By using photos in conjunction with such a VTL installation, restoring data during a blackout is greatly reduced.

A large number of tape backup applications already employ some form of tape virtualization. If you have specific requirements in this regard, you should contact your software vendor. So how does the entire system work?

The flow of the operation

Operationally, the environment does not change and the scheduled backups still work as installed. Installation of hardware and software may require some installation depending on the equipment already installed with connectivity details (IP, SCSI, iSCSI, Fibre Channel) according to the network topography.

With more configuration and infrastructure, a more dynamic and fault-tolerant solution can be installed – all without the expense, support costs and tape recycling schedules. Figure A represents an example of a VTL configuration.

What exactly does virtualization bring to this configuration? Virtualization has the potential to completely avoid tape support of the topography. As mentioned above, there are products available that can create multiple virtual libraries or tape machines. The advantage is that multiple backups can operate from different servers in the same storage pool.

The storage can perform a less rigorous backup to tape, or another VTL. This second tier VTL can be slower disk storage and functions as a continuous backup of the first tier backup. Easy access to products that facilitate the creation of VTL environments along with inexpensive technology has made it possible to process dual backups with different schedules.

Lena S. O'Reilly