What the RAID mean in the Hard drive and what does it do?

Answer 1

REdundant Array of Inexpensve Disks.

In a nutshell, it gets many hard drives to function as one drive.

it is used to either gain additional storage space, for redunancy, or for speed.

There are many types of raid available which are too much to go into here.

Answer 2

It used to be "Redundant Array of Inexpensive Disks" but now the Inexpensive gets replaced with "Independent" frequently.

It's just a way to spread data files across a bunch of hard drives so that if one crashes you can still get to your files, or your server will still run fast, or still be secure, etc.

There are several types of RAID and they require setting up which can be quite complex.

I wrote some technical documents about RAID for both Intel and HP - do a search on either web site and you'll get some things back that explain RAID in much greater detail.

Answer 3

Like the previous answerer said, RAID makes two or more hard drives function as one. A common application of RAID is placing the same data on two or more drives, so that you don't lose your data if a hard drive dies on you.

The TechWeb Encyclopedia link below has a lot more info about RAID. Happy reading!

Answer 4

Same as guy said above.

Most common raid type is raid 0, which is purely for speed. It has no redundancy and will have an overall storage capacity of the two drives combined.

Answer 5

Redundant array of independent disks.... depending on the type of RAID 0 to 5 it allows for greater fault tolerance with regards to hardware ware and data. Your data is spread across multiple drives so if one fails there is no loss.

Answer 6

A complete & comprehensive description of RAID & all its levels from 0 to 50.

http://www.acnc.com/04_01_00.html

regards,
Philip

Answer 7

RAID = Redundant Array of Inexpensive Disks

RAID refers to a data storage scheme using multiple hard drives to share or replicate data among the drives. Depending on the configuration of the RAID (typically referred to as the RAID level), the benefit of RAID is one or more of increased data integrity, fault-tolerance, throughput or capacity compared to single drives. In its original implementations, its key advantage was the ability to combine multiple low-cost devices using older technology into an array that offered greater capacity, reliability, speed, or a combination of these things, than was affordably available in a single device using the newest technology.

At the very simplest level, RAID combines multiple hard drives into a single logical unit. Thus, instead of seeing several different hard drives, the operating system sees only one. RAID is typically used on server computers, and is usually (but not necessarily) implemented with identically sized disk drives. With decreases in hard drive prices and wider availability of RAID options built into motherboard chipsets, RAID is also being found and offered as an option in more advanced personal computers. This is especially true in computers dedicated to storage-intensive tasks, such as video and audio editing.

The original RAID specification suggested a number of prototype "RAID levels", or combinations of disks. Each had theoretical advantages and disadvantages. Over the years, different implementations of the RAID concept have appeared. Most differ substantially from the original idealized RAID levels, but the numbered names have remained. This can be confusing, since one implementation of RAID 5, for example, can differ substantially from another. RAID 3 and RAID 4 are often confused and even used interchangeably.

The very definition of RAID has been argued over the years. The use of the term redundant leads many to object to RAID 0 being called a RAID at all. Similarly, the change from inexpensive to independent confuses many as to the intended purpose of RAID. There are even some single-disk implementations of the RAID concept. For the purpose of this article, we will say that any system which employs the basic RAID concepts to combine physical disk space for purposes of reliability, capacity, or performance (or even sociability — see the Just a Bunch Of Disks discussion) is a RAID system.

What RAID Can Do

* RAID can protect uptime. RAID levels 1, 0+1/10, 5, and 6 (and their variants such as 50 and 51) allow a mechanical hard disk to fail while keeping the data on the array accessible to users. Rather than being required to perform a time consuming restore from tape, DVD, or other slow backup media, RAID allows data to be restored to a replacement disk from the other members of the array, while being simultaneously available to users in a degraded state. This is of high value to enterprises, as downtime quickly leads to lost earning power. For home users, it can protect uptime of large media storage arrays, which would require time consuming restoration from dozens of DVD or quite a few tapes in the event of a disk failing that is not protected by redundancy.

* RAID can increase performance in certain applications. RAID levels 0, and 5-6 all use variations on striping, which allows multiple spindles to increase sustained transfer rates when conducting linear transfers. Workstation type applications that work with large files, such as image and video editing applications, benefit greatly from disk striping. The extra throughput offered by disk striping is also useful in disk-to-disk backups applications. Also if RAID 1 or a striping based RAID with a sufficiently large block size is used RAID can provide performance improvements for access patterns involving multiple simultaneous random accesses (e.g., multi-user databases).

What RAID Cannot Do

* RAID cannot protect the data on the array. A RAID array has one file system. This creates a single point of failure. A RAID array's file system is vulnerable to a wide variety of hazards other than physical disk failure, so RAID cannot defend against these sources of data loss. RAID will not stop a virus from destroying data. RAID will not prevent corruption. RAID will not save data from accidental modification or deletion by the user. RAID does not protect data from hardware failure of any component besides physical disks. RAID does not protect data from natural or man made disaster such as fires and floods. To protect data, data must be backed up to removable media, such as DVD, tape, or an external hard drive, and stored in an off site location. RAID alone will not prevent a disaster from turning into data loss. Disaster is not preventable, but backups allow data loss to be prevented.

* RAID cannot simplify disaster recovery. When running a single disk, the disk is usually accessible with a generic ATA or SCSI driver built into most operating systems. However, most RAID controllers require specific drivers. Recovery tools that work with single disks on generic controllers will require special drivers to access data on RAID arrays. If these recovery tools are poorly coded and do not allow providing for additional drivers, then a RAID array will probably be inaccessible to that recovery tool.

* RAID cannot provide a performance boost in all applications. This statement is especially true with typical desktop application users and gamers. Most desktop applications and games place performance emphasis on the buffer strategy and seek performance of the disk(s). Increasing raw sustained transfer rate shows little gains for desktop users and gamers, as most files that they access are typically very small anyway. Disk striping using RAID 0 increases linear transfer performance, not buffer and seek performance. As a result, disk striping using RAID 0 shows little to no performance gain in most desktop applications and games, although there are exceptions. For desktop users and gamers with high performance as a goal, it is better to buy a faster, bigger, and more expensive single disk than it is to run two slower/smaller drives in RAID 0. Even running the latest, greatest, and biggest drives in RAID-0 is unlikely to boost performance more than 10%, and performance may drop in some access patterns, particularly games.

* RAID is not readily moved to a new system. When using a single disk, it is relatively straightforward to move the disk to a new system. Simply connect it to the new system, provided it has the same interface available. However, this is not so easy with a RAID array. A RAID BIOS must be able to read metadata from the array members in order to successfully construct the array and make it accessible to an operating system. Since RAID controller makers use different formats for their metadata (even controllers of different families from the same manufacturer may use incompatible metadata formats) it is virtually impossible to move a RAID array to a different controller. When moving a RAID array to a new system, plans should be made to move the controller as well. With the popularity of motherboard integrated RAID controllers, this is extremely difficult to accomplish. Generally, it is possible to move the RAID array members and controllers as a unit, and software RAID in Linux and Windows Server Products can also work around this limitation, but software RAID has other limitations (mostly performance related).


Here's a link for more about RAID :
http://en.wikipedia.org/wiki/RAID

Fell free to contact me ^_^