RAID2 - Bitlevel Striping + Hamming ECC- RAID2 is a 'wierd' RAID level in that, like other RAID levels that implement striping (at a byte level), RAID2 does so at a bit-level. A Hamming ECC (see this for a more indepth look at Hamming ECC) parity is stored across all the drives
- Since parity is generated at the bit-level, any errors detected can be fixed on the fly (byte-level parity cannot do so since there are 8-bits per byte and an even number of errors will go undetected)
- The primary feature of RAID2, the bit-level ECC, is actually what makes RAID2 somewhat useless -- modern harddrives feature this anyways (i.e., you get this feature for free) and as such RAID2 is not used in modern configurations
- The advantage of RAID2 is exceptional read speads since the data is split across very many drives however the downside is that (a) write speed is not so great due to the overhead of dealing with on-the-fly parity generation and validation and (b) numerous drives are required to implement RAID2 making it inefficient
- No commercial implementations exist (or at least viable ones), however drive requirements are very high
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