What is SATA raid?

Answer 1

RAID stands for Redundant Array of Independent Disks (originally Redundant Array of Inexpensive Disks). It is a technology that provides increased storage functions and reliability through redundancy. There are several different types of RAID -

• RAID 0 just spreads a file between different disks. This speeds up data storage and retrieval. Of all the types of RAID, this one alone does not provide increased reliability because there is no redundancy. It can, however, be combined with other RAID types to get the protection.

• RAID 1 writes the same data to 2 disks so if one disk fails you still have a backup on the other disk.

• RAID 2 (bit-level striping with dedicated Hamming-code parity) has all disk spindle rotation synchronized, and data is striped such that each sequential bit is on a different disk. Hamming-code parity is calculated across corresponding bits on disks and stored on at least one parity disk. If one disk fails, the original data can be reconstructed from the rest of the disks as long as the Hamming-code parity is still available.

• RAID 3 is much like RAID 2 except that it is sequential BYTES that are stored on different disks with parity calculated and stored separately

• RAID 4 and RAID 5 are the same except that RAID 4 stores all parity data on a single drive while RAID 5 spreads it out among the drives. They distribute the data between drives and require all drives but one to be present to operate; the array is not destroyed by a single drive failure. Upon drive failure, any subsequent reads can be calculated from the distributed parity such that the drive failure is masked from the end user. A single drive failure still results in reduced performance of the entire array until the failed drive has been replaced and the associated data rebuilt.
• RAID 6 is like RAID 5 except that it uses doubledistributed parity so that the system can continue to function while the data is rebuilt even if a second drive fails during the rebuild process.

Different types of RAID's can be combined for additional protection; for example in RAID 1+0: (a.k.a. RAID 10) mirrored sets in a striped set (minimum four disks; even number of disks) provides fault tolerance and improved performance but increases complexity. The array can sustain multiple drive losses so long as no mirror loses all its drives.

Serial ATA (SATA or Serial Advanced Technology Attachment) is a computer bus interface for connecting host bus adapters to mass storage devices such as hard disk drives and optical drives. Serial ATA was designed to replace the older ATA (AT Attachment) standard (also known as EIDE), offering several advantages over the older parallel ATA (PATA) interface: reduced cable-bulk and cost (7 conductors versus 40), native hot swapping, faster data transfer through higher signalling rates, and more efficient transfer through an (optional) I/O queuing protocol.

SATA RAID is thus RAID implemented using SATA. Since SATA supports hot swapping and most types of RAID allow operations to continue even with the loss of a single drive, failed drives in a SATA RAID can be hot swapped without shutting down the system.