hesela.devSymbol erasure
A symbol erasure is a codeword position whose value is unavailable or deliberately discarded and whose location is known to the decoder.
An erased value is not a zero, and an incorrect value at an unidentified position remains an error. The distinction is part of the decoder input contract, not a diagnosis of why storage failed. [1] Hesela's six-symbol example shows that identifying the actual damaged coordinate enables recovery, whereas discarding a healthy coordinate can leave a unique wrong result. [2]
Relations
- related
- error-and-erasure-decoding, reed-solomon-code, erasure-coding, codeword, checksum
Limitations
- A checksum mismatch only helps locate an erasure when the check and the fragment identity are trustworthy.
- Erasing an entire shard affects its mapped symbol positions; counts must be interpreted per codeword.