* Redundant array of independent disks ( RAID )-This method generalizes the device mirroring above by allowing one device in a group of N devices to fail and be replaced with content restored ( Device mirroring is RAID with N = 2 ).

However, if a second failure occurs before the RAID group is completely repaired from the first failure, then data can be lost.

Thus the probability of two failures in a same RAID group in time proximity is much smaller ( approximately the probability squared, i. e., multiplied by itself ).

If a database cannot tolerate even such smaller probability of data loss, then the RAID group itself is replicated ( mirrored ).

* Redundant array of independent disks ( RAID )-This method generalizes the device mirroring above by allowing one device in a group of N devices to fail and be replaced with content restored ( Device mirroring is RAID with N = 2 ).

However, if a second failure occurs before the RAID group is completely repaired from the first failure, then data can be lost.

Thus the probability of two failures in a same RAID group in time proximity is much smaller ( approximately the probability squared, i. e., multiplied by itself ).

If a database cannot tolerate even such smaller probability of data loss, then the RAID group itself is replicated ( mirrored ).

In practice redundancy is provided both in the form of additional connectivity from server to the network as well as in the servers themselves, using features like RAID 5 or better, distributed server ( multiple networked servers appearing as one server to the users ), VMWare High Availability and Fault Tolerance or Citrix XenApp's load balancing.

If an XFS filesystem is to be created on a striped RAID array, a stripe unit can be specified when the file system is created.

When an XFS filesystem is used on a logical device provided by a hardware RAID controller with battery backed cache, this feature can cause significant performance degradation, as the filesystem code is not aware that the cache is nonvolatile, and if the controller honors the flush requests, data will be written to physical disk more often than necessary.

A disk array typically has cache ( temporary memory storage that is faster than the magnetic disks ), as well as advanced functions like RAID and storage virtualization.

RAID ( redundant array of independent disks, originally redundant array of inexpensive disks ) is a storage technology that combines multiple disk drive components into a logical unit.

Data is distributed across the drives in one of several ways called " RAID levels ", depending on what level of redundancy and performance ( via parallel communication ) is required.

RAID is now used as an umbrella term for computer data storage schemes that can divide and replicate data among multiple physical drives.

The physical drives are said to be " in a RAID ", however the more common, incorrect parlance is to say that they are " in a RAID array ".

Following is a brief textual summary of the most commonly used RAID levels.

For example, if three drives are arranged in RAID 3, this gives an array space efficiency of ( approximately 66 %); thus, if each drive in this example has a capacity of 250 GB, then the array has a total capacity of 750 GB but the capacity that is usable for data storage is only 500 GB.

For example, if each of three drives has a failure rate of 5 % over the next 3 years, and these drives are arranged in RAID 3, then this gives an array failure rate of over the next 3 years.

For example, computer RAID disk arrays allow a faulty disk to be hot-swapped for a new one ; the new one is configured to become part of the array automatically or by user command.

For example, a " redundant RAID ( redundant array of inexpensive / independent disks )" may in fact be a backup RAID in the system being described, " laser ( light amplification by stimulated emission of radiation ) light " is light produced by a light amplification process, " CSS ( cascading style sheets ) sheet " is used to express a sheet written in the language.

CLARiiON was an early commercial example of a RAID product and initially sold exclusively as an array with the company's Aviion line of computer systems.

( It may also be necessary to load chipset-specific AHCI or RAID drivers — from a USB Flash drive, for example — at installation time.

During special events, the RAID is also in charge of protecting French individuals abroad ( For example, the French Delegation during the Olympic Games is under RAID protection during the whole event ).

In connection with RAID, for example, this allows for seamless replacement of failed drives.

Such RAID arrays, both of " managed " ( for example, SANs and NASs ) and " unmanaged " ( for example, JBoDs on a single computer workstation ), are necessary due to the enormous throughput required for real-time ( 320 MB / s for 2K @ 24fps ) or near-real-time playback in post-production, compared to throughput available from a single, yet fast, hard disk drive.

* Dylan, a high-performance RAID storage system by Quantel

Database servers are usually multiprocessor computers, with generous memory and RAID disk arrays used for stable storage.

NAS systems are networked appliances containing one or more hard drives, often arranged into logical, redundant storage containers or RAID arrays.

Servers also typically have fault tolerant features, such as redundancy in power supplies, storage ( as in RAID ), and network connections.

However the storage is attached, the drives themselves are usually configured as a Redundant Array of Inexpensive ( or Independent ) Discs RAID, which may be configured to provide appropriate combination of faster disk access or protection against the failure of one ( or even two ) discs in the physical RAID array.

* External RAID controllers designed by LSI Corporation and used in IBM System Storage's DS3000 and DS4000 ( formerly FAStT ) plus some storage systems from Silicon Graphics, Sun Microsystems / StorageTek, Teradata, Dell, Fujitsu, Sepaton, BlueArc and several other companies worldwide

In RAID devices and SANs and where logical drives ( LUNs ) are composed via LUN virtualization and aggregation, LBA addressing of individual disk should be translated by a software layer to provide uniform LBA addressing for the entire storage device.

NAS systems are networked appliances which contain one or more hard drives, often arranged into logical, redundant storage containers or RAID arrays.

NAS systems contain one or more hard disks, often arranged into logical, redundant storage containers or RAID arrays.

Devices and / or systems that have been described as mass storage include tape libraries, RAID systems, hard disk drives, magnetic tape drives, optical disc drives, magneto-optical disc drives, drum memory ( historic ), floppy disk drives ( historic ), punched tape ( historic ) and holographic memory ( experimental ).

Striping is used across disk drives in RAID storage, network interfaces in Grid-oriented Storage, and RAM in some systems.

* 2006: September, Introduced desktop RAID storage

* Many bits are stored on RAID storage systems.

** Disk storage – RAID / NAS / SAN technologies.

The company provides an interconnect and controller product family for both 3G and 6G SAS / SATA storage systems and Server RAID.

Dr. Gibson's principal contribution to computing was developing the RAID taxonomy of redundant data storage systems, along with David A. Patterson and Randy Katz.

Recent events ( increase in processor speed, lower cost terabyte disk storage, RAID drive functionality, etc.

Similarly, using a journaling file system and RAID storage will only protect against certain types of software and hardware failure.