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Advanced data backup technology and protection fundamentals

Start developing business opportunities based on Advanced data backup technology can develop business opportunities based on the latest developments in tape, disk, and remote and strategic storage concepts.

Handling enterprise data backup technology for any size business means keeping the business running while meeting the necessary compliance requirements. The best data backup strategy for a customer must also take into account security and government regulations. While this guide may not be for those brand new to backup, it will offer some fundamental insights to anyone who wants to start taking advantage of advanced backup features and the latest developments in tape, disk, and remote and strategic storage concepts.

Tape backup

On the surface, it's easy to select tapes --- just buy cartridges that fit the tape drives in your customer's enterprise. But today, the choice is more complicated than that. Tapes are expensive and you must understand how those expenses will ultimately impact your return on investment. High-end LTO-3 tapes can cost over US$60 for a 400 GB-to-800 GB cartridge, while a Quantum digital linear tape (DLT) 0.8-to-1.6 terabyte (TB) tape can start at US$120 each.

Although tape backups are slower than disk backups, tape drives are getting faster. For example, today's SuperDLT drives can support 60 megabytes per second (MBps), uncompressed, while late-model linear tape open (LTO) drives can handle 80 MBps, uncompressed. Sun Microsystems Inc. introduced the T10000 tape drive in late 2005, touting a data throughput of 120 MBps with uncompressed capacities up to 500 GB on a single cartridge. The biggest difficulty with "fast" tape drives is that host backup servers generally cannot accommodate those data rates, often resulting in wasted efficiency -- fast tape requires careful design of the communication path between the drive and backup server, and between the server and storage.

Today, groups within an organization are sharing fewer tape libraries, so there's a push to pay only for the library capacity being used -- yet they want to maintain management control over the tapes in that portion of the library, presenting you with a few business opportunities. Consequently, tape libraries are incorporating partitioning and chargeback features, as well as greater scalability for consolidation. The Scalar i500 from Advanced Digital Information Corp. (ADIC) provides partitioning and chargeback, and scales from one to 18 LTO drives, and 36 to 404 tape slots in a single frame. Partitioning can also be found in libraries like IBM's TS3310, the TLS series from Qualstar Corp. and the CSM200 from Sony Electronics Inc. It's interesting to note that library features like multiple tape media support, high availability and large numbers of tape drives are not as popular as once thought.

Data backup software is moving beyond the role of scheduling and reporting -- another area you should be paying attention to as a VAR or systems integrator. Users are turning to backup software to reduce the sheer data backup size. Compression had been used to fit more data onto a given tape, but data deduplication, also called intelligent compression or commonality factoring, is starting to appear. Deduplication works by saving a single iteration of a file or block -- providing only pointers to duplicated data. That is, instead of saving 10 copies of a 10 MB sales presentation, only one copy is actually saved to tape.

Data backup on disk

Low cost and relatively high performance have made hard disks the preferred target for many data backup tasks. Regardless of the actual storage platform, there are several important trends worth presenting to your customers.

First, data deduplication is appearing on data backup platforms like virtual tape libraries (VTL) and content addressed storage (CAS) archives. Deduplication reduces the number of disks needed for storage or fits more data into available space -- lowering the disk investment.

As the amount of data relegated to secondary disk expands, the retention period for secondary disk is also increasing. Data backups might typically reside on a secondary disk platform for several weeks or perhaps a month before being offloaded to tape for long-term off-site storage. This is changing as larger arrays of inexpensive disks enter service. CAS systems are already managing long-term data retention on disk, and VTL storage arrays might soon hold a year's worth of data.

You must also consider the effects of power, cooling and reliability in large data backup disk installations. Arrays with hundreds of disks can consume thousands of watts of power which is difficult to cool properly, and cumulative disk vibration can cause premature disk failures -- especially among SATA drives. Array manufacturers like Copan Systems are developing MAID systems where 80% of the disks are idle. The idle disks are powered on and tested periodically. Data is migrated between disks to ensure that all disks are used for the same time -- reducing power and improving mean time between failures (MTBF).

Remote data backup

The ongoing challenge with remote data backups is the cost of bandwidth. A company must budget for connectivity that supports an appropriate backup volume within an acceptable backup window. Too much bandwidth wastes money; too little bandwidth wastes time. Deduplication and selective backups reduce data and lower bandwidth needs.

The choice between synchronous and asynchronous replication can have a significant impact on data backups. Synchronous replication offers the lowest recovery point objective (RPO) and recovery time objective (RTO), but the latency of long geographic distances can render this impractical. Asynchronous replication is a little easier, can work across longer distances and is tolerant of WAN outages. But asynchronous RPOs can range into hours because remote writes can lag significantly behind local writes.

WAN reliability is another consideration that is often overlooked. A failed WAN link can disable the data backup process, potentially leaving critical data at risk. Organizations should investigate an alternative that can protect data during a WAN interruption. For example, you may implement a backup to local disk and then pass the disk backup to an off-site VTL or other disk system. If the WAN fails, there is already a local backup, and the remote backup can be retried or completed once the WAN is available.

Other data backup concepts

Traditionally, data backups were implemented to suit the individual needs of the organization, ensuring that important data could be recovered in an emergency. Mirroring, replication, snapshots and continuous data protection (CDP) technologies are still commonly employed for exactly that purpose. Many disk storage platforms routinely include applications to support these features. For example, the Clariion CX3 Model 80 from EMC Corp. includes SnapView software for local replication and MirrorView software for remote replication.

Today's data backups are increasingly influenced by compliance and corporate governance concerns that require data to be integral, accessible and retainable for a prescribed length of time. As a VAR or systems integrator you must work with a customer to understand what data should be backed up; how the data should be backed up and protected; and how the data is accessed in the face of legal discovery or disaster. Backup planning for compliance should involve business units across the enterprise -- not just IT. CAS systems are often employed to meet compliance obligations since CAS platforms offer data deduplication, security and data management/search tools that are suited to long-term data retention and retrieval.

Security is also gaining importance, and backup administrators must protect sensitive or personal information against loss. Backup software like Symantec Corp.'s NetBackup offers encryption as an option, allowing tape or disk data to be encrypted during data backup, or decrypted for recovery. Still, there is some debate about just "where" encryption should take place. Software encryption is effective, but it reduces performance and locks an organization into the backup software product. By comparison, encryption can also be performed at the tape drive itself (like Sun's T10000), through a dedicated appliance, such as the CryptoStor family from NeoScale Systems Inc., or the DataFort family from Decru Inc. In the disk-to-disk (D2D) storage realm, VTL products are embracing encryption, and FalconStor Software Inc., includes a Secure Tape Transport Service module with its VTLs.

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