7.2. RAID Technology Overview

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RAID is an acronym for redundant array of independent disks. RAID is a group of disk drives that the host system sees as a single large device. The purpose of RAID is to set up fault-tolerant and fast disk arrays.

RAID technology is based on the theory that a group of smaller drives is more efficient than one large drive. The basic premise of fault-tolerant RAID is that an intelligent drive controller, or manager, can handle a drive array so that it can withstand the failure of any individual drive in the array without losing data.

RAID storage offers major benefits over nonarrayed storage systems, including the following:

  • Performance The RAID system distributes data and I/O requests among all members of the drive array. Each drive in the array helps process the I/O requests, which increases concurrency and can increase overall performance.

    Note

    Fault-tolerant RAID configurations incur a performance penalty based on how the fault tolerance is configured.


  • Data availability and reliability The RAID system enables you to employ a fault-tolerant configuration that duplicates portions or all of the stored data, protecting the information against loss because of a failed disk. Many RAID solutions can automatically recover from a disk failure, and often provide continuous I/O service to the hosting environment.

  • Dynamically increased storage capacity A RAID system can expand storage capacity well beyond the capacity of a single disk system. Many RAID solutions are dynamic, enabling you to add disks to expand the array.

  • Simplified storage management The RAID system combines many smaller disk drives into one or more virtual disks with the desired capacity, data availability, and performance. This allows management of mass storage consolidated into a single array.

7.2.1 JBOD

Just a bunch of disks (JBOD) is a storage option that connects one or more standalone disk drives to the RAID controller or other drive controller of a server. This option increases capacity and is used for noncritical business data.

The JBOD drive does not become part of a RAID array, but it is made available to the server on the same interconnect bus as the other devices controlled by the RAID controller. The JBOD disk drive has no data redundancy or striping.

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    HP ProLiant Servers AIS. Official Study Guide and Desk Reference
    HP ProLiant Servers AIS: Official Study Guide and Desk Reference
    ISBN: 0131467174
    EAN: 2147483647
    Year: 2004
    Pages: 278

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