SOURCE: Diskeeper Corporation

June 18, 2008 13:55 ET

Automatic Defrag Allows RAID to Provide the Full Benefit for Which it Was Intended

BURBANK, CA--(Marketwire - June 18, 2008) - Two prime objectives when it comes to computing are protection and integrity of data, and improving system throughput and performance. Many millions -- if not billions -- of dollars have been spent in the pursuit of both these goals. One major breakthrough for both of them has been RAID (Redundant Array of Independent Disks) technology, and defrag is of vital assistance to this technology.

For data protection and integrity, RAID provides for data to be written redundantly so that if one physical drive fails that data is still fully accessible and recoverable. This functionality also does much to increase performance; since the I/O load is across several disks instead of just one, retrieval is faster. An operating system can even perform simultaneous seeks on more than one disk and have simultaneous reads or writes occurring.

The file system "sees" the data in a RAID set as one virtual volume and performs its reads and writes accordingly. If data on the physical disks is fragmented, it will also appear as fragmented in the virtual volume and will take longer to retrieve in ratio to the number of fragments per file. Additionally, RAID necessitates several extra steps when reading or writing a file -- RAID hardware/software must process any file request and determine to which physical member to direct the I/O request -- so a RAID system must work that much harder when fragmentation exists. The result is that the performance benefit is negated to the degree that files are fragmented.

A fully automatic defrag solution such as Diskeeper® sees the RAID environment just as the file system does. That is, it defragments the logical drive, improving the speed and performance of a RAID environment by eliminating wasteful and unnecessary I/Os. More system time can be dedicated to doing real useful work for the users and applications. Diskeeper works invisibly in the background to keep a RAID set consistently defragmented, utilizing idle resources whenever they are available. Performance is not negatively impacted by the defrag process, and scheduling is never required.

Diskeeper is a perfect complement to RAID, allowing its data integrity and performance benefits to be fully realized.

For more information, this is a newly released white paper: "How Is Defragmentation Affected by New Storage Technologies?" The paper is also located at:

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