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Raid Level 0
"Striped set without parity" or "Striping". Provides improved performance and additional storage but no fault tolerance. Any disk failure destroys the array, which becomes more likely with more disks in the array. A single disk failure destroys the entire array because when data is written to a RAID 0 drive, the data is broken into fragments. The number of fragments is dictated by the number of disks in the array. The fragments are written to their respective disks simultaneously on the same sector. This allows smaller sections of the entire chunk of data to be read off the drive in parallel, giving this type of arrangement huge bandwidth. RAID 0 does not implement error checking so any error is unrecoverable. More disks in the array means higher bandwidth, but greater risk of data loss.
Q: What is a "RAID 0″ configuration?
A: A RAID 0 (zero) volume set is a group of hard disk drives that are combined and accessed together based on a pre-defined configuration to allow for "data striping" across multiple drives. The term "RAID" refers to a "Redundant Array of Inexpensive (or Independent) Disks". RAID 0 drive sets are also described as "striped without parity" and "non-redundant" volumes.
Q: What is meant by the term "disk striping"?
A: Within a disk striping (RAID 0) volume, information will be written evenly , or "striped", over at least 2 (if not more) disk drives.
Q: How many drives are needed for a RAID 0 volume?
A: To establish a RAID 0 volume, a minimum of at least 2 hard disk drives ar required. Unlike RAID 1, the number of drives used in the array can be an odd or even number.
Q: What is the difference between "hardware" and "software" RAID 0 configurations?
A: Hardware-based RAID 0 uses a physical controller (either as a separate plug-in board or as part of the motherboard) that provides for the striping of data across the drives in the volume. With a software-based RAID 0 volume, the drives are attached to a normal drive contoller and software controls the order and writing to drives in the volume set.
Q: What are the benefits of using drives set up as a RAID 0?
A: A RAID 0 (disk striping) set will use the maximum amount of available storage capacity of each drive in the array, and allows for faster access and retrieval of data.
Q: What are the negatives associated with RAID 0?
A: RAID 0 (disk striping) does not provide any protection against drive failures. If one or more drives fail, all of the information contained on the volume becomes totally inaccessable. On the other hand, with a mirrored disk volume (RAID 1), information is written to the first drive and then to a second (or "mirror") drive at the same time. If one of the hard drives in the mirror volume fails, the remaining hard drive can be placed in service as a single drive with no loss of information. Similar to a RAID 0 volume, RAID 1 volumes require a minimum of two (2) drives.
Q: Can RAID 0 be combined with another type of RAID, like RAID 1?
A: The combination of striping and then mirroring is referred to as RAID 0+1. In this scenario, the configuration will provide disk striping (RAID 0) across 2 or more drives and will "mirror" the data in real-time to a duplicate drive set (RAID 1). This unique combination will provide fault tolerance, but it does so at the expense of usable storage space. A volume established as a RAID 0+1 volume will need four (4) hard drives at a minimum to be configured.
Q: Can data be recovered from a re-formatted RAID 0 volume?
A: Many times information is still recoverable, depending on how the drives were re-formatted. Re-formatting a volume using Windows, for example, will create what will appear to be a new "clean" volume - but the original data will still be on the disk in the "free and available" space. A low-level format to "wipe" or overwrite every single block takes a considerable amount of time and destroys the original data.
Q: Could data recovery software utilities be used to recover my RAID 0?
A: Perhaps, but it wouldn't be the safest approach. Most data recovery software will require the read / write heads to constantly travel over areas of the original disk that, if there is any physical damage, could render the surfaces useless and beyond recovery. The safest method of recovering data from a failed or corrupted RAID 0 volume (or with any storage device) is to create a block-level copy of every sector on each hard drive. The copied image is then used to reconstruct the original volume and rescue the required files and directories. This approach, while more time consuming, maintains and preserves the data integrity of the drive media and limits the number of times that the original drive needs to be accessed. It also protects against any writing to the original media, which could result in an inadvertent overwrite of the data that needs to be recovered.
Q: With RAID 0, if one or more drives become corrupted or fail, is data recoverable?
A: In most situations, data will be recoverable. The quality and integrity of the data recovered will depend on the extent of the damage incurred to each failed storage device. The drives will need to be addressed and recovered individually before attempting to address the set as a volume.