Monday, 5 November 2012

Types of RAID Array Configurations and Data Recovery Services

Types of RAID Array Configurations and Data Recovery Services

There are many types of RAID array configurations like RAID 0, RAID 1, RAID 3, RAID 5, RAID 6, RAID 10, RAID 50, JBOD (SPAN) Recovery. We will discuss all types of RAID array configurations in detail. We will also discuss how to recover RAID data from various RAID configurations.

1. RAID 0 Configuration and Data Recovery

A RAID 0 requires a minimum of two hard disks. Data is striped between the disks in increments of either 64 or 128 KB (normally). This configuration offers no protection against data loss, since there is no parity information for redundancy. The RAID 0 setup does, however, offer increased performance. Because of multiple drives reading a single file at the same time, read performance from the array is higher. There is less of a difference on write time, and performance ratio decreases as the number of drives in the array increases.

2. RAID 1 Configuration and Data Recovery

A RAID 1 configuration requires at least two hard drives. Also known as mirroring, everything written to the first drive is also written to the second. RAID 1 provides excellent data protection, because if one drive fails all of the data is still available on the second drive. This array takes a hit to performance since all data must be written twice. From a data recovery standpoint, both disks must still be evaluated to determine the best way to extract a users data.

3. RAID 3 Configuration and Data Recovery

A RAID 3 requires at least three hard disks, and it introduces the concept of parity. Parity is a block of data that is not user accessible, but is an XOR calculation result of the user data written to the other drives. If any of the hard drives fail, data can be reconstructed by reversing the XOR equation. There is a slight lag in performance because this calculation takes a small amount of additional time.

4. RAID 5 Configuration and Data Recovery

RAID 5 is one of the most common configurations. This array uses the same parity calculation as a RAID 3, however, instead of placing all of the parity on a single drive, it distributes it throughout all of the hard disks. There are four standard patterns for writing parity, Left Asynchronous stripe is depicted here. The width of the stripe or the amount of data that is written to each location can vary dramatically. The capacity and performance equations of a RAID 5 are very similar to that of a RAID 3.

5. RAID 6 Configuration and Data Recovery

A RAID 6 array takes RAID 5 to the next level. Current controllers utilized for this array are more expensive so most of these are maintained by high level IT firms and companies. Instead of a single stripe of parity, a RAID 6 produces two stripes. In theory this means that any two hard drives in the array can fail at the same time and the data can still be reconstructed. There is an additional delay in writing to this array as the controller must calculate two sets of parity.

6. RAID 10 Configuration and Data Recovery

A RAID 10, also known as 1+0, requires at least four hard disks. This array is set up as a mirrored stripe, combining the standards from a RAID 1 and a RAID 0. This array is often used for OS and application servers. Due to the larger amount of required hard disks, the overhead is typically higher when implementing a RAID 10 array. Data is very secure in this array, as one entire RAID can fail and data is still accessible.

7. RAID 50 Configuration and Data Recovery

A RAID 50, also known as 5+0, requires at least 6 hard disks. This array utilizes mirrored parity by combining the standards from a RAID 5 and a RAID 0. This array provides added security against data loss, however, due to the overhead costs and performance issues, most IT directors chose RAID 6 standards if this type of data protection is required.

8. JBOD Configuration and Data Recovery

A JBOD (Just a Bunch of Disks) is a simple concatenation or spanning of multiple physical disks. This distant relative of RAID is often used to combine several hard drives together to create one larger virtual hard drive. JBOD offers no redundancy and no performance advantages. Normally this type of setup is used when an after-market hard drive is added to an existing system to increase storage space. The available capacity of a JBOD is the sum of all disks. For example if a 35GB, a 60GB, and a 100GB drive were set up in a JBOD configuration, your available space would be 195GB of storage space.

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