RAID Frequently Asked Questions

The following knowledgebase is very small, but does reflect some of the more basic questions our RAID recovery technicians receive on a daily basis. It is our hope to gradually build this into a page with far more substantial content, but in the meantime, it is a reasonable guide to RAID systems.

Certainly, if your question is not answered by this FAQ, or if your RAID issue is an emergency, we definitely recommend you contact us immediately for help. Having a RAID expert on your side during failure can save you not only time, but money.

Q: What does the term "RAID" stand for?

A: R.A.I.D., despite its usual abbreviated RAID form, is in fact an acronym for “Redundant Array of Inexpensive Disks” (the “I” is sometimes defined as “Independent”). A RAID set is a group of two or more hard disk drives that are collected together based on a pre-set configuration in order to provide either data mirroring, data striping or redundancy, and in most forms, a combinations of all of the above.

In past years, RAID systems tended to be enterprise level only because of their reliance on expensive SCSI drives. Recently, however, motherboard manufacturers have begun building RAID capabilities to even low end PC desktop systems, as hard disk drives have become cheaper and cheaper to manufacture with high capacities and high speeds available.

Q: How many RAID levels are currently available today?

A: The RAID level number represents the differing configurations of a RAID system, and define its speed and backup capabilities. RAID systems can have an infinite number of non-standard configurations, but the most common currently defined RAID systems include 0, 1, 2, 3, 4, 5, 6, 10 (also known as RAID 1+0), 50 (or RAID 5+0), 100 (or RAID 10+0) and RAID 0+1. The most common forms of RAID currently used for both enterprise and consumer applications are the basic RAID 1 and RAID 5.

Q: What is the minimum number of hard disk drives required in order to create a RAID?

A: The minimum number of hard drives necessary in order to create a RAID is 2. The RAID 0 and RAID 1 systems can each be created with two drives, as each are focused on different benefits. The RAID 0 is a simple striping array with a focus on disk performance, and no redundancy. A RAID 1, meanwhile, focuses solely on mirroring, with no performance advantages. The RAID 5 volume requires three drives, and is frequently configured with more. The number of drives required usually goes up from there, with the higher level RAID systems requiring far more drives.

Q: What are the key differences between hardware controlled RAID systems and software controlled RAIDs?

A: Because the prices of RAID equipped hardware controllers and built-in motherboard controllers have come down so much recently, software RAID systems are far less popular than they were but a few years ago.

The Software RAID system is typically used via operating system (with Windows and Mac versions typically used), and use the main disk controller while the software manages the array drives. Hardware RAID systems are far more robust and performance-effective because they use a special physical controller that both controls data write and read functions and maintains hard drive information. They avoid the downside of software RAIDs because they do not require the use of CPU and memory resources, instead using the processors within the card or board.

Q: My RAID setup has failed. Should I use a recovery software utility to attempt to recover it?

A: Using data recovery software can be the solution, but depending on the problem, it can be very risky to use. In cases where data has been lost because of physical damage to the hard drive, it can be catastrophic, as it may corrupt and destroy even more data as the drive heads pass over the damaged drive platter. In some cases, this can make the data unrecoverable altogether.

At RAID Data Recovery Services Group, our RAID recovery techniques are the safest possible, as we use a technique which enables us to individually recover each storage block on each drive or disk. From this, we can create drive images which enable us to rebuild the original array structure and recover lost files and folders. This is a critical approach, as it severely limits the interaction with the original data device, which may be damaged.

Q: Multiple drives have failed in my RAID array. Can I recover the data?

A: This type of RAID recovery is the one we specialize in. Whether as the result of damage to multiple physical drives or complete RAID structure loss, RAID Data Recovery Services Group provides this form of recovery several times per day, 24/7, 365 days per year.

Q: Can data be recovered from an accidental (or intentional) RAID reformat?

A: In many cases, yes, but this depends on how heavily the drive has been reformatted. Most drive reformats that have been provided by operating systems (Windows is the main example) will quickly establish a logical drive volume, but will leave most or all of the physical data alone on the disk.

Meanwhile, as controller-level format may, in “quick format” mode, only write over the array information while leaving data intact. Deeper formats, however, including those that overwrite data block-by-block, may be far more dangerous, as they may actually completely overwrite your data. The best thing to do is ask an expert.

Q: I would like RAID Data Recovery Services Group to recover my RAID system. What should I send?

A: In order to perform an effective RAID recovery, we may only need the original RAID system drives. Depending on the situation, we may also ask for the original RAID controller as well. In many cases this may not be possible, such as when the controller is built into the motherboard. Shipping drives and controllers is a very important job which must be done correctly in order to ensure that shipping and delivery does not damage the drives. Please call us first before you ship your drives, and ensure you check out our hard drive shipping checklist here.

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