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Cheap SATA spurs D2D

New disk-to-disk (D2D) backup appliances complement -- and in some cases replace -- traditional tape backup.

This article first appeared in "Storage" magazine in their October issue. For more articles of this type, please visit

What you will learn from this tip: How low-cost serial ATA disk arrays will reduce data volumes and save money.

Two vendors are capitalizing on falling disk prices to create disk-to-disk (D2D) backup appliances that complement -- and in some cases replace -- traditional tape backup. By combining low-cost serial ATA (SATA) disk arrays with software that greatly reduces the amount of data required to be backed up and then further compresses it, these products can back up a company's data using a fraction of the storage capacity required by a conventional backup process.

Going a step further, the compressed backup can be sent over a WAN to another disk appliance at a remote site to produce an off-site backup copy -- D2D2D, as it were. The pared down data stream requires comparatively little bandwidth, making it significantly less expensive than conventional remote data replication.

Data Domain Inc., Palo Alto, Calif., offers the DD200 Restorer, a storage backup and recovery appliance built around SATA disks, plus its proprietary data reduction and compression technology. That software segments the data into chunks as small as 2 KB and backs up each chunk only once. Combined with its Replicator product, Data Domain says it can transmit backed up data across a WAN to a remote appliance using 99% less network resources than other disk-based backup and recovery products.

Avamar Technologies Inc., Irvine, Calif., provides similar capabilities with its Axion product line. Axion analyzes the backed up data to identify small snippets of data that have already been backed up. It then condenses and compresses what's left over. As a result, the volume of data to be backed up amounts to one-half of 1% of the total versus 10% using conventional data reduction and compression techniques, says Kevin Daly, CEO. Furthermore, the more data Axion has "seen" before, the less capacity it will require to back it up down the road.

"Both companies reduce the amount of data to be backed up. The reduced data requires less disk media, which lowers the cost of storage," says Tony Asaro, analyst, Enterprise Strategy Group, Milford, Mass. Either product can reduce 20 TB of data to about 1 TB on disk. "Then you can mirror that 1 TB to a remote site and your WAN costs will be much lower," he continues. Recovery of data will be faster too because both products leverage the random access capabilities of disk to recover single files.

Although the vendors' products are similar, they differ in a fundamental way. Data Domain allows users to run their regular backup process using its standard backup software, for example Veritas' NetBackup or BackupExec -- it just looks like another backup target. Avamar, on the other hand, uses its own proprietary backup software. "Avamar basically reinvents the backup process," says Asaro.

Read more of this tip in Storage magazine.

For more information:

Tip: How to prevent common problems in SATA drives

Tip: Steeling SATA for duty

Advice: Advantages of ATA and SATA disk drives

About the author: Alan Radding is a freelance writer located in Boston.

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