Network Appliance deploys new RAID technique

The new version of Network Appliance Inc.'s NearStore data storage appliance features a new form of RAID storage architecture, said Richard Scurfield, regional director for defense and intelligence sales for the federal subsidiary of the Sunnyvale, Calif.-based company.

RAID is short for redundant array of independent disks. It is a collection of techniques for spreading information across multiple disks such that if any one disk fails the data can be fully recovered from the other disks.

Network Appliance's NearStore uses a technique called Double Parity RAID, sometimes referred to as RAID-DP. According to a Network Appliance white paper, this form of RAID, unlike others, can recover data if more than one disk fails at any one time.

Most RAID techniques work by adding the number of bits in data blocks across multiple disks, the total of which is kept on a separate disk. If one disk fails, the data can be recovered by simply subtracting the sum of the remaining bits from the total stored on the parity disk. Double Parity uses a second parity disk, which adds bits diagonally across different rows of data blocks.

The latest version of NearStore, released earlier this year, incorporates RAID-DP. The vendor is marketing NearStore as a low-cost alternative to network attached storage or to cheaper, though slower, nearline magnetic tape storage systems, Scurfield said.

Network Appliance is not the first storage vendor to try RAID-DP. For instance, Hewlett-Packard Co. has used RAID-DP in some of its Surestore line of enterprise storage systems. Scurfield said previous implementations of RAID-DP by other vendors have had only limited success due to sluggish performance. He claimed Network Appliance's version of the RAID adds only a three percent overhead to read and write speeds.

NearStore systems can hold up to 96T of data and start at about $7 dollars per gigabyte for basic configurations.

NearStore uses off-the-shelf commercial hard drives along with the company's own file management system. By using serial ATA disks, the company can offer nearly the same performance and reliability of a full-fledged NAS unit, but at a portion of the cost, said Mark Weber, vice president and general manager of Network Appliance's federal practice.

Network Appliance's latest government customers include the Office of Naval Intelligence and the Army's Personnel Command, Scurfield said.

About the Author

Joab Jackson is the senior technology editor for Government Computer News.

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