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Diagram of a RAID 1 setup. RAID 1 consists of an exact copy (or mirror) of a set of data on two or more disks; a classic RAID 1 mirrored pair contains two disks.This configuration offers no parity, striping, or spanning of disk space across multiple disks, since the data is mirrored on all disks belonging to the array, and the array can only be as big as the smallest member disk.
RAID 6 requires a minimum of four disks. As with RAID 5, a single drive failure results in reduced performance of the entire array until the failed drive has been replaced. [11] With a RAID 6 array, using drives from multiple sources and manufacturers, it is possible to mitigate most of the problems associated with RAID 5.
RAID 01, also called RAID 0+1, is a RAID level using a mirror of stripes, achieving both replication and sharing of data between disks. [3] The usable capacity of a RAID 01 array is the same as in a RAID 1 array made of the same drives, in which one half of the drives is used to mirror the other half.
For example, a RAID 1 array has about half the total capacity as a result of data mirroring, while a RAID 5 array with n drives loses 1/n of capacity (which equals to the capacity of a single drive) due to storing parity information. RAID subsystems are multiple drives that appear to be one drive or more drives to the user, but provide fault ...
a mixture of disk drives configured as RAID 1 (2D+2D and 4D+4D) and RAID 5 (3D+1P and 7D+1P). up to 1024 disk drives for 288 GB to 149 TB raw and 144 TB to 129 TB of usable storage capacity in a single array; heterogeneous connectivity via Fibre Channel, iSCSI, FICON and ESCON; up to 128 GiB battery-protected (48 hours minimum), mirrored write ...
CLARiiON was an early commercial example of a RAID product and initially sold exclusively as an array with the company's Aviion line of computer systems as the HADA (High Availability Disk Array) and later the HADA II [6] before being made available for broader open systems attachment and renamed CLARiiON in 1994. [7]
Those external disk arrays are usually purchased as an integrated subsystem of RAID controllers, disk drives, power supplies, and management software. It is up to controllers to provide advanced functionality (various vendors name these differently): Automatic failover to another controller (transparent to computers transmitting data)
With a software implementation, the operating system manages the disks of the array through the normal drive controller (ATA, SATA, SCSI, Fibre Channel, etc.). With present CPU speeds, software RAID can be faster than hardware RAID. A hardware implementation of RAID requires at a minimum a special-purpose RAID controller.