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Parchive: Parity Archive Volume Set
DISCLAIMER: This project web space is not actively mantained and is presented here for archive purposes. However some project members still montior the project mailings lists if you have questions.
The original idea behind this project was to provide a tool to
apply the data-recovery capability concepts of RAID-like
systems to the posting and recovery of multi-part archives
on Usenet. We accomplished that goal. Our new goal with
version 2.0 of the specification is to improve. It extends
the idea of version 1.0 and takes the recovery process beyond
the file-level barrier. This allows for more effective protection
with less recovery data, and removes some previous limitations
on the number of recoverable parts. See
Par1 compared to Par2
for a more detailed view of the differences.
Because this new approach doesn't benefit from like sized files,
it drastically extends the potiental applications of PAR. Files
such as video, music, and other data can remain in a usable format
and still have recovery data associated with them.
The technology is based on a 'Reed-Solomon Code' implementation that allows for recovery
of any 'X' real data-blocks for 'X' parity data-blocks present. (Data-blocks
referring to files OR much smaller virtual slices of files).
The key to this mission is a clean file format specification
which provides all the necessary capabilities for programs
to easily verify and regenerate single missing parts
out of a set of data-blocks.
Current clients come in one of two flavors:
Those supporting v1.0 of the spec. (Currently extremely popular
on Usenet). And those adopting the v2.0 of the spec, touting all the benefits
of this newer approach.
Only time will tell how Version 2.0 fares in the Usenet community, wish us luck.
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