RAID is an acronym that stands for Redundant Array of Independent Disks, and as this suggests, combines multiple hard-drives that work together, so that if one hard-drive goes down, your data storage does not. A basic RAID configuration might be Raid 1, or Raid 0.

Raid 1 is a basic raid setup where two disks are used together, and data is “mirrored” from one disk to another. The two disks are considered to be one disk as far as your operating system is concerned, and will continue to function as long as one disk remains operating. The advantage of Raid 1 is you can lose one drive and keep going. The disadvantage is if you use two drives say of 500GB, you only get 500GB of space, not 1TB. So you lose half of the space you’d normally have out of those two drives. So you’re trading space for redundancy.

Raid 0 isn’t really raid at all, and is where two or more disks are used together to increase the size of a virtual raid disk. For example, three 1TB drives work together to make one 3TB drive. The raid configuration also provides improved performance. The problem with this is, if one disk out of your three dies, then you lose the entire array. For this reason, Raid 0 isn’t used a great deal, except in combination with Raid 1. For example you could have two virtual raid 0 disks combined with Raid 1, so you get an increase in performance and redundancy thrown in. Using the examples above you could have a 3TB raid array combining raid 1 and raid 0, but that would cost you six 1TB drives.

Another way to do it, is to use raid 5. A raid 5 array distributes the data across the total amount of disks, increasing performance and at the same time providing redundancy. Using our six 1TB drives in raid 5 configuration, we would end up with a 5TB raid array. If any of the six disks go down, the array continues to operate, as it automatically uses data from the remaining five to reconstruct the data from the sixth. The array will have a reduced performance until the broken drive is replaced, but all data will be intact. The only way you can lose data with a raid 5 drive is if two drives fail at the same time, which is highly unlikely. You can even configure a hot spare drive, that isn’t used in the raid array for any purpose except to be added should one of the main drives goes down. The hot spare can then be converted to an array drive and you continue until you install a replacement.

So to summarize, raid 5 allows you to store data with increased disk performance, and also allows you to lose one drive to failure without affecting your data.

The two most known and popular RAID schemes are RAID 0 and RAID 1. Raid 0 is a scheme were multiple drives are used to improve the data read and write performance. This is achieved by utilizing all drives in the read and write process, instead of just one if no raid would be used. The increased speed comes at the cost of a higher data loss risk, as a single disk failure will destroy the RAID array so that the data cannot be accessed anymore.

Raid 1 utilizes the disks in a different way. It is generally known as a mirroring scheme, as all disks of the array store copies of the data. The benefit of this scheme is that there is always an immediate backup available if one of the disks fails, the disadvantage that half the combined space is used for the mirroring. Raid 1 causes only a small performance drop.

Raid data recovery has been created to troubleshoot and repair raid arrays. The effectiveness of the tool depends largely on the type of failure that is experienced.

RAID recovery is a free software program that can repair the following raid related parameters:

• Start offset and block size
• Number of member disks
• Member disks and data order
• Parity position and rotation

Preparations are needed to use the tool effectively. The most important aspect is to know exactly which hard drives are included in the raid, and which type of raid array needs to be recovered. For hardware raids, it is furthermore necessary to disconnect drives from a hardware raid before the raid can be recovered. We suggest to write down the exact setup to be able to recreate it at a later time.

raid data recovery

Raid Recovery supports creating a disk image, which can be used for the recovery instead of a damaged drive. Then, all drives that are part of the setup need to be selected. The program displays the relevant information in its interface.

• For RAID 0 select a minimum of two devices from the list and click Start RAID 0
• For RAID 0+1 and 1+0, select all the available member disks and click Start RAID 0. It is required to select a minimum of two disks.
• For RAID 5, select all the available member disks and click Start RAID 5. Minimum of two disks is required. ReclaiMe Free RAID Recovery software can recover RAID 5 with one disk missing.

Finally, after the disks have been selected the raid can be recovered by clicking on Start Raid 0 or Raid 5 in the program interface. This can take anywhere from a few minutes to a few hours. Data recovery may be needed in the end to recover data that has been damaged on the drives.

Raid Recovery is a free nice to have program that can be used to repair common raid failures. The program is compatible with 32-bit and 64-bit editions of the Windows operating system, and available for download at the developer website.

OCZ on the other hand seems to be one of the driving forces in SSD technology at this point in time. Their OCZ Vertex drives look really promising in both read and write performance. Old Solid State Drives usually excelled in read performance but lacked the necessary write performance.

Their latest hardware that was first shown at the Cebit in Germany is the OCZ Z-Drive. This piece of computer hardware is connected via PCI Express to a computer system taking up two slots because of its dimensions. It is made up of four 256 Gigabyte MLC-based OCZ Solid State Drives and 256 Megabytes of ECC DDR2 RAM. This adds up to a total storage capacity of 1 Terabyte and promises maximum read rates of 600 MB/s and read rates of 500 MB/s. The sustained write speed is said to be 400 MB/s.

The only drawback is the hefty price tag which is expected to be between $1500 and $2000. The OCZ Z-Drive is expected to be available in April 2009 with additional models following later this year.

The Raid Tutorial explains all Raid modes (0,1,2,3,4,5,6,10,50,0+1) in a great way. You see a diagram which explains the dataflow visually. Below the diagram is an characteristics & advantages and a disadvantages as well as one for recommended applications. Take a look, its great, fast loading and does not take to much time to understand the Raid concept and which you should chose if you want to switch to Raid.

[tags]raid, raid  system, Redundant Array Of Independent Disks, hard drive, hard disk, hd, mirror[/tags]