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Advanced Storage Options
Some advanced storage options such as Redundant Array of Independent/
Inexpensive Drives (RAID) and Global Network Block Device (GNBD) are discussed
in this section.
Redundant Array of Independent/Inexpensive
Drives
RAID is a data storage scheme for dividing and replicating data among multiple
hard disk drives. It spreads data among several physical hard drives with enough
redundancy so that should any drive fail, the data will still be intact. Once created,
a RAID array is a device that can be used pretty much like a regular partition.
It provides increased data reliability and greatly improved input and
output performances.
The three key concepts in RAID are as follows:
Mirroring: Copying the data to more than one disk.
Striping: Splitting the data across more than one disk and reading sequences
of data simultaneously off multiple disks.
Fault tolerance: Increasing the reliability of the system by storing some
redundant data, so that problems can be detected and possibly fixed quickly.
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The biggest advantage of using RAID is that systems can be designed to keep
working when there is failure??”hot swapping of disks and automatic data recovery
even while the system keeps running. For this reason RAID is often used in high
availability systems, where it is critical that the system keeps running for as much of
the time as possible. The following resources will help you to get Xen working using
RAID storage:
??? Setting up Xen with LVM and RAID:
http://www.
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