Implementing secondary storage using disk-as-disk, where data is backed up to a standard file-system format, requires an alternate method of getting the right data copied, at the right time—after all, backup software typically writes to tape, using a tape-compatible format.
Increasingly, backup software vendors are adding support for disk-as-disk backup but this support is new and not necessarily as robust as some backup environments require. Even after you add disk-as-disk, your strategy to write data to tape remains necessary. Best practices and—in many companies, legal mandates—require longer-term archival storage, often for years. That means that disk-as-disk complicates your data protection efforts. You have to add diskas-disk equipment, and software that supports it, while retaining existing backup strategies and tape libraries.
VTLs Without Complexity: Spectra Logic RXT" Sabre" as VTLAPR I L 2006WHITE PAPERUntitled Document2RXT and Sabre are trademarks, and Spectra, TeraPackand the Spectra Logic are registered trademarks of Spectra Logic Corporation. All rights reserved worldwide. All other trademarks and registered trademarks are the property of their respective owners. All library features and specifications listed in this white paper are subject to change at any time without notice. Copyright 2006 by Spectra Logic Corporation. All rights reserved.VTLs Without ComplexityCONTENTSExecutive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Increased Reliability and Performance . . . . . . . . . . . . . . . . . . . . . . . . . . .4Backup Environment Continuity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Easier to Implement than Disk-as-Disk. . . . . . . . . . . . . . . . . . . . . . . . . . .4Easily Scaled. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4VTLs: Some Disadvantages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Complexity in Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Additional Data Center Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Finding the Virtual Tapes Storing your Data . . . . . . . . . . . . . . . . . . . . . . .5Finding Tapes Copied from VTL using VTL commands. . . . . . . . . . . . . . . . .6Case Study: VTL Disadvantages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6RXT Sabre as VTL: All the Advantages without Any of the Disadvantages . 7RXT Sabre as VTL: Second Generation . . . . . . . . . . . . . . . . . . . . . . . . . . .7RXT Sabre as VTL: All the Advantages of VTL . . . . . . . . . . . . . . . . . . . . . .7RXT Sabre as VTL: Solves First-Generation VTL Disadvantages . . . . . . . . . .8RXT Sabre as VTL: Additional Advantages. . . . . . . . . . . . . . . . . . . . . . . . .9Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Untitled DocumentVTLs Without Complexity: Spectra Logic s RXT Sabre as VTL3Executive SummaryAs IT data centers begin to embrace disk as a viable medium in secondary storage, virtual tape libraries (VTLs) fill an important niche between primary storage and archival storage on tape. Disk in the form of VTLs that is, disk presented as tape can be added without requiring huge changes to existing backup strategies. This compares favorably to adding disk into an existing environment, because adding disk without the VTL interface requires complex and unavoidable changes to existing strategies. This simplicity, coupled with the affordability of SATA disk for short-term storage, has turned VTL into a viable storage option. First generation VTLs are gradually moving into data centers.First generation technology typically has drawbacks a useful new technology, or a new variation on an existing technology, is almost certain to have problems. By virtue of being new, a product offers options to users that weren t there before. It takes time to integrate new technology, and with field-use, technological and usability issues become evident. The technology can then be refined, taking it to the next level.First generation VTLs do have problems, primarily complexity of setup. Secondarily, and perhaps directly related to complexity, VTLs often have problems with the real-world performance versus theoretical gains. Spectra Logic s RXT Sabre addresses all the first generation VTL drawbacks and consequently goes a step further, adding features that expand beyond first generation VTL (disk-as-tape) products. Untitled DocumentVTLs Without Complexity: Spectra Logic s RXT Sabre as VTL4VTL: Many AdvantagesThe advantages that VTLs bring to secondary storage have led to the increasingly widespread deployment of VTLs in backup environments.Increased Reliability and PerformanceVTLs deliver backup and restore reliability and performance. Problems associated with tape drives have encouraged IT administrators to look toward disk to reduce the length of time it takes to backup data and to increase the reliability of backups. VTL is the first application to ease the addition of disk to existing backup environments.Backup Environment ContinuityPerhaps the most appealing aspect of VTLs is that they let you add disk to the backup environment while enabling you to continue using your existing backup strategy and software. After all, sites typically already have backup software that copies data from primary disk, then writes the data in a tape format. By putting the VTL between the backup server and the physical tape library, the disk can instantly be used, because it appears to the external backup environment as tape, and so you have added disk without disrupting existing backup strategies.Easier to Implement than Disk-as-DiskImplementing secondary storage using disk-as-disk, where data is backed up to a standard file-system format, requires an alternate method of getting the right data copied, at the right time after all, backup software typically writes to tape, using a tape-compatible format.Increasingly, backup software vendors are adding support for disk-as-disk backup but this support is new and not necessarily as robust as some backup environments require. Even after you add disk-as-disk, your strategy to write data to tape remains necessary. Best practices and in many companies, legal mandates require longer-term archival storage, often for years. That means that disk-as-disk complicates your data protection efforts. You have to add disk-as-disk equipment, and software that supports it, while retaining existing backup strategies and tape libraries.Easily ScaledThe ability to expand a VTL is very important. Data grows, rather than shrinks, and every secondary storage system should readily accommodate data growth. If your VTL doesn t scale easily, then the potential advantages of VTLs are outweighed by this major disadvantage. Untitled DocumentVTLs Without Complexity: Spectra Logic s RXT Sabre as VTL5VTLs: Some DisadvantagesVTL s advantages have led to the success of disk-as-tape hardware and software. However, the success has also revealed flaws inherent in typical first-generation VTL design. Complexity in InstallationVTLs are very hard to install and configure, adding complexity to the already-complex process of protecting data. This complexity threatens to overshadow the advantages of the VTL. To act as virtual tape, the VTL needs to be fully characterized. The size of the virtual tapes, the number of data streams, number and type of virtual tape libraries, individual processes, and more have to be defined and implemented. Often, VTLs require months with the help of expensive professional services staff from the VTL vendor to setup and optimize. This complexity detracts from one of the advantages of VTL: that VTLs don t require changes to existing backup strategy. The reason for maintaining an existing strategy is to simplify backup. If VTLs fit in, but add complexity in doing so, the benefit of simplicity is lost.Additional Data Center SpaceData protection best practices absolutely requires some form of off-site data storage with a lengthy archival shelf-life of years or decades. For most sites, that means tape. Tape is affordable, proven, and already in use in virtually every data center.Because storing data to tape is likely to remain necessary, adding VTL doesn t mean that you can replace your tape library. Instead, adding traditional VTL simply means another piece of equipment, with all the attendant demands: space, power for cooling and for operating the VTL, an additional point of management, an additional service level agreement, and another component to merge into existing networks and backup strategies. The VTL adds another layer of physical and administrative overhead.Finding the Virtual Tapes Storing your DataOne possibly unanticipated drawback of VTLS is the difficulty you can have in recovering the virtual tape containing the data that is to be restored. If your VTL is large and your backups are complicated, it can be difficult to find the right virtual tape holding the data that you need to restore. This is a significant drawback to VTL.Untitled DocumentVTLs Without Complexity: Spectra Logic s RXT Sabre as VTL6Finding Tapes Copied from VTL using VTL commandsSome VTLs provide disk-to-tape copy commands. On first glance, this appears to be an advantage; but as it turns out, this feature is also a liability. Copies of data are only useful if you have some way of tracking those copies, and one thing that backup software does well is associate data with the bar-coded tape on which the data is stored. This is simply not available with VTLs, since the tapes are virtual.Don t Scale or Don t Scale WellAll secondary storage needs to be able to expand as data growth escalates. One disadvantage to traditional VTLs is that, as with almost all disk, typically the only way to scale capacity or throughput is adding controllers and capacity. This coupling of performance and capacity is a very costly method of scaling when you only need either capacity or throughput.Case Study: VTL DisadvantagesChildren s Hospital Boston is an important pediatric medical and research center. With continuous data growth building on a base of 60 TB of data, the center needs to be able rely on backups completed within tight time constraints, and that support ready data recovery. At the same time, Children s Hospital IT operations have been plagued with backup problems. A lot of people were losing sleep over our backup environment, said Paul Scheib, Director of Operations and Chief Information Security Officer at Children s.Although Children s Hospital Boston tried using VTL to address these difficulties, the VTL system they implemented was simply not manageable. VTLs made the backup environment more complicated and simply added to administrators headaches. Configuration and administrative issues grew rather than declined. The VTL constituted yet another piece of equipment with which the data center staff had to deal.As VTLs are increasingly implemented, case studies such as this illustrate VTL drawbacks painfully so, for Children s Hospital Boston.Untitled DocumentVTLs Without Complexity: Spectra Logic s RXT Sabre as VTL7RXT Sabre as VTL: All the Advantages without Any of the DisadvantagesSpectra Logic s RXT SabreDrive solutions offer the advantages of VTL, and as a second generation VTL product, RXT Sabre also overcomes VTL s characteristic disadvantages. RXT Sabre goes further than first generation VTLs, using innovation to provide advantages not found in any other VTL solution.RXT Sabre as VTL: Second GenerationRXT Sabre as VTL implements an innovative approach to backup that yields dividends of simplicity and affordability. Unlike most VTLs, which simply incorporate off-the-shelf fixed SATA disk, RXT Sabre supports barcoded, removable SabreMedia RAID disk packs. Unlike other VTLs, the disk is tracked with a physical, not a virtual, barcode. This barcode helps you easily identify and track data on the disk, which may be onsite or offsite.RXT SabreDrives conceptually parallel standard tape drives. SabreDrives write data to physical SabreMedia packs. Adding capacity is as simple as adding more SabreMedia just as you can add more tape cartridges as to store your increasing quantities of data.RXT Sabre as VTL: All the Advantages of VTLRXT Sabre as VTL lets you add disk to your existing backup infrastructure easily and without requiring strategy change. This simplicity lets you add the reliability and performance of disk without overhauling your backup processes. It is also easier to implement than disk-as-disk, because RXT Sabre doesn t require an additional layer of backup procedures and provisioning requirements. RXT Sabre is also easily scaled, so that Sabre-as-VTL keeps pace with data growth.RXT SabreDrives and RXT SabreMediaThe RXT Sabre family of products includes SabreDrives and SabreMedia. Each RXT SabreDrive matches the size of a standard tape drive that handles LTO or other half-inch tape.RXT SabreDrives write to portable media RXT SabreMedia composed of multiple Serial ATA (SATA) disks sealed in an enclosure that tolerates rugged handling. RXT SabreMedia is further protected by additional shock dampening technology incorporated into the media.RXT Sabre is available in three configurations. The SabreDrive D150 is a stand-alonedrive. The SabreDrive D350 is rack-mounted unit with three drive bays housing RXT SabreDrive(s) and optionally tape drives. The RXT SabreDrive for the Spectra T950 library integrates and automates RXT SabreMedia RAID. Hot-pluggable RXT SabreDrives simply slide into the library. RXT SabreDrive as VTL can be easily added to any backup environment. You don t need to change existing backup strategies and policies, and you don t need to add servers, software licenses, or applications. Further, installing and configuring the RXT SabreDrive takes minutes, not days and no consultants are necessary. Although backup applications see the packs as virtual tapes, the packs that hold the tape s data are real, as are the drives that write to the packs. That makes the setup easy and the virtual tapes (bar-coded RXT SabreMedia packs) easy to identify. RXT SabreDrive scales like tape, rather than requiring the large scaling increments of VTL. Because RXT SabreMedia is mobile RAID, you can store the disk offline and offsite with the added protection of RAID. 12 SATA drives in an RXT SabreMedia pack Untitled DocumentVTLs Without Complexity: Spectra Logic s RXT Sabre as VTL8RXT Sabre as VTL: Solves First-Generation VTL DisadvantagesUnlike all other VTLs, RXT Sabre is as easy to add to your backup environment as adding another tape drive. You don t need to configure a myriad of characteristics to force the disk to appear to the environment as a tape drive. Instead, you simply add an RXT SabreDrive. Backup software already knows how to stream data to tape drives. With RXT Sabre, configuration issues simply disappear. Instead of requiring days and months of installation and set up, you can add RXT SabreDrives in minutes.One of the advantages of the RXT Sabre VTL becomes instantly obvious: you can scale either performance or capacity, or both. To scale only capacity, add SabreMedia packs; to scale only performance, add SabreDrives. This holds true for the SabreDrive D150, the SabreDrive D350, and for SabreDrives in the Spectra T950 library. Further, the Spectra T950 library can expand to a six-frame maximum, letting you scale from gigabytes to petabytes of data on both disk and tape.The cost savings of RXT Sabre versus other VTLs are huge: sites can now add VTL without adding, integrating, using, and managing another piece of stand-alone equipment. Further, sites with Sabre as VTL don t have additional service level agreements, additional energy costs associated with running and cooling the new equipment, and additional data center space demands. The simplicity of installation, integration, and management of RXT-Sabre-as-VTL in a Spectra T950 library is unmatched by any other VTL available.If you opt for a smaller VTL, you still gain. The RXT SabreDrive D150 and D350 take up minimal real estate and have minimal energy and cooling requirements. Because the SabreDrive is as easy to add as adding a tape drive, the installation is simple and fast.SabreDrive uniquely solves another problem that no other VTL can; with SabreMedia, virtual tapes physically correspond to bar-coded media packs. The advantage to this, compared to other VTLs, is the one-to-one relationship between a virtual tape and a physical media unit. A SabreMedia pack with a barcode can be physically tracked and located.RXT Sabre as VTL maintains data integrity and data ownership because it does not allow you to create isolated virtual tapes that are not tracked by backup software. This way, the backup software knows of every copy of data, so you don t end up with disk that has no easily identifiable and therefore readily retrievable content. Without a consistent method of data identification and tracking, you risk losing the copy of the data, and eventually losing access to the disk storing the data. The disk is lost because the copy of data, taking up the disk, may remain untracked and so never expire.Untitled DocumentVTLs Without Complexity: Spectra Logic s RXT Sabre as VTL9RXT Sabre as VTL: Additional AdvantagesRXT SabreMedia s mobility is a truly innovative advantage over traditional VTLs. The data, protected by RAID, can be left near online within the data center, or moved offline or even off site, providing a comprehensive data protection solution simply not available through any other VTL. The correspondence between a virtual tape and the physical media corresponding to a virtual tape further simplifies integration and use issues. Instead of having to alter perception to accept that the backup is virtual, the physical media is evident and can be tracked easily using bar codes. data controlled by backup softwaredata to/from VTL via backup softwaredata under VTL controlVTL software configuration: define streams, virtual drives, virtual tapes and libraries, processes... VTL VTL created copies location unknown to backup softwareTape Library Scaling: Add Another VTLServer COMPLEXITYConfiguring Common VTLSIMPLICITYConfiguring Sabre VTLServerT950 with Disk and TapeUntitled DocumentVTLs Without Complexity: Spectra Logic s RXT Sabre as VTL10ConclusionVTLs are establishing themselves as valid backup storage options. The first generation of VTLs took some years to earn this validity. As with all new technology, however, field-use has brought to light some disadvantages associated with typical VTLs.Spectra Logic s RXT Sabre as VTL provides an extremely intuitive and practical implementation of VTL, addressing the shortcomings of first generation products while expanding the flexibility and advantages this solution provides.The Spectra T950 library with RXT Sabre VTL and tape is particularly illustrative of the value of Spectra Logic s unique and complete data protection solutions. By incorporating RXT SabreDrives, SabreMedia, tape drives, and tape cartridges into a single Spectra T950 library, administrators gain simplicity while taking full advantage of VTL. Further, because SabreDrives and SabreMedia can be scaled independently of each other, RXT Sabre gives administrators the option of expanding capacity, performance, or both, rather than requiring data centers to pay for both in lockstep, as is the case with traditional VTLs. Finally, although the tape is virtual, SabreMedia are physical, bar-coded packs, making it easy to find data that needs to be restored. These advantages help VTLs step up to their initial promise in simplifying the addition of disk, with its reliability and performance advantages, to any backup environment.ReferencesData Domain. Children s Hospital Case Study, Customer Success. www.datadomain.comPreston, Curtis W. Pros and Cons of VTLs, Storage Magazine, April 2005.www. storagemagazine.techtarget.com Storage Provisioning, www.searchstorage.techtarget.com/sDefinitionUntitled Documentwww.SpectraLogic.comSpectra Logic Corporation1700 N 55th StreetBoulder Colorado 80303 USA800.833.1132303.449.6400Spectra Logic Europe LimitedMagdalen CentreRobert Robinson AvenueOxford Science ParkOxford UK OX44 7 RW+44 (0) 870.112.2150