PAR - Revision history

Speckmade: PAR2 moved to PAR: general name of the software - without the version number

2007-06-14T14:14:31Z

PAR2 moved to PAR: general name of the software - without the version number

← Older revision	Revision as of 14:14, 14 June 2007
(No difference)

Speckmade at 14:14, 14 June 2007

2007-06-14T14:14:02Z

← Older revision		Revision as of 14:14, 14 June 2007
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	* [http://www.dvdisaster.com/ dvdisaster]: Although not exactly PAR, dvdisaster uses the Reed-Solomon algorithm to create a correction file for a DVD image		* [http://www.dvdisaster.com/ dvdisaster]: Although not exactly PAR, dvdisaster uses the Reed-Solomon algorithm to create a correction file for a DVD image
	* [http://www.hydrogenaudio.org/forums/index.php?showtopic=31146 HA Thread: "Parchive, subdirectory"]: A useful thread discussing PAR2 tactics		* [http://www.hydrogenaudio.org/forums/index.php?showtopic=31146 HA Thread: "Parchive, subdirectory"]: A useful thread discussing PAR2 tactics


			[[Category:Software]]

Speckmade at 14:12, 14 June 2007

2007-06-14T14:12:07Z

← Older revision		Revision as of 14:12, 14 June 2007
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	PAR (''parity'') files are created from a source file or files (''recovery set''), and can be used to restore the recovery set if any file becomes corrupted.		PAR (''parity'') files are created from a source file or files (''recovery set''), and can be used to restore the recovery set if any file becomes corrupted.

	Many Hydrogen Audio members back-up their [[CD]] collection, and a good proportion of these archive their files using [[DVD]]. Optical media is prone to aging, and aging will lead to sector errors and file corruption. The use of PAR2 data can help you to restore a partially corrupted archive, allowing you the luxury of reburning the reconstructed files to a new disc. If you create parity data, and check your DVD archive regularly, there is no reason why you cannot continue this process ad infinitum, or at least until [[DVD]]s become obselete.		Many Hydrogen Audio members back-up their [[Compact Disc Digital Audio\|AudioCD]] collection, and a good proportion of these archive their files using [[DVD]]. Optical media is prone to aging, and aging will lead to sector errors and file corruption. The use of PAR2 data can help you to restore a partially corrupted archive, allowing you the luxury of reburning the reconstructed files to a new disc. If you create parity data, and check your DVD archive regularly, there is no reason why you cannot continue this process ad infinitum, or at least until [[DVD]]s become obselete.

			= PAR =
	=PAR=		PAR files were widespreadly used for Usenet newsgroup multi-part archive files. When posting a file a user could also post PAR files which would allow downloaders to recover any part of the archive by downloading an equal number of PAR files. I.e.: if two parts of the archive were missing or corrupt the downloader would just need to download ''any two'' PAR files and they could successfully recreate the archive.

	PAR files were widespreadly used for Usenet newsgroup multi-part archive files. When posting a file a user could also post PAR files which would allow downloaders to recover any part of the archive by downloading an equal number of PAR files. I.e.: if two parts of the archive were missing or corrupt the downloader would just need to download ''any two'' PAR files and they could successfully recreate the archive.

	PAR files are named as follows:		PAR files are named as follows:
			* filename.PAR
	*filename.PAR		* filename.P01
	*filename.P01		* filename.P02
	*filename.P02		* filename.P03
	*filename.P03		* etc.
	*etc.

	The .PAR file is simply a small (~1KiB) index file for the set, and does not contain any parity data.		The .PAR file is simply a small (~1KiB) index file for the set, and does not contain any parity data.

			= PAR2 =
	=PAR2=

	PAR2 succeeded PAR; its main benefit being that there is no relationship between the size of the source files and the size of the PAR2 files, ''and'' that undamaged blocks in a corrupt PAR2 file can still be used to recover the recovery set. The [http://www.quickpar.org.uk/AboutPAR2.htm QuickPar] website has a good description of the main differences between the two formats.		PAR2 succeeded PAR; its main benefit being that there is no relationship between the size of the source files and the size of the PAR2 files, ''and'' that undamaged blocks in a corrupt PAR2 file can still be used to recover the recovery set. The [http://www.quickpar.org.uk/AboutPAR2.htm QuickPar] website has a good description of the main differences between the two formats.

	PAR2 files are named as follows:		PAR2 files are named as follows:

	* filename.PAR2		* filename.PAR2
	* '''filename.vol<span style="color:red">nnn</span>+<span style="color:purple">mm</span>.PAR2'''		* '''filename.vol<span style="color:red">nnn</span>+<span style="color:purple">mm</span>.PAR2'''
	**'''<span style="color:red">nnn</span>''' is the starting block number for this file, and the total number of blocks of all preceding files<br>		** '''<span style="color:red">nnn</span>''' is the starting block number for this file, and the total number of blocks of all preceding files<br />
	**'''<span style="color:purple">mm</span>''' is the number of recovery blocks in this file, and therefore the number of blocks it can repair		** '''<span style="color:purple">mm</span>''' is the number of recovery blocks in this file, and therefore the number of blocks it can repair


	Therefore, if your recovery set becomes corrupt and your PAR2 client tells you that you need nine blocks to repair the set, you will need to utilise a number of PAR2 files whose <span style="color:purple">mm</span> values add up to nine, or more. This may be "filename.vol000+01.PAR2" and "filename.vol007+08.PAR2", or solely "filename.vol015+14.PAR2".		Therefore, if your recovery set becomes corrupt and your PAR2 client tells you that you need nine blocks to repair the set, you will need to utilise a number of PAR2 files whose <span style="color:purple">mm</span> values add up to nine, or more. This may be "filename.vol000+01.PAR2" and "filename.vol007+08.PAR2", or solely "filename.vol015+14.PAR2".
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	Although you may create PAR2 files with a total of 200 recovery blocks, on repairing you only need to utilise those PAR2 files that contain enough blocks to repair the damage to your recovery set.		Although you may create PAR2 files with a total of 200 recovery blocks, on repairing you only need to utilise those PAR2 files that contain enough blocks to repair the damage to your recovery set.

			= How Does It Work? =
	=How Does It Work?=

	The redundant data in the PAR files is computed using the Reed-Solomon algorithm 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 redundant data in the PAR files is computed using the Reed-Solomon algorithm 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).

	For more information read [http://parchive.sourceforge.net/docs/specifications/parity-volume-spec/article-spec.html the full PAR 2.0 specification].		For more information read [http://parchive.sourceforge.net/docs/specifications/parity-volume-spec/article-spec.html the full PAR 2.0 specification].

			= Links =
	=Links=		* [http://parchive.sourceforge.net/ Parchive: Parity Archive Tool]: Home of PAR
			* [http://www.quickpar.org.uk/ QuickPar]: A superb PAR/PAR2 GUI
	*[http://parchive.sourceforge.net/ Parchive: Parity Archive Tool] : Home of PAR		* [http://www.dvdisaster.com/ dvdisaster]: Although not exactly PAR, dvdisaster uses the Reed-Solomon algorithm to create a correction file for a DVD image
	*[http://www.quickpar.org.uk/ QuickPar] : A superb PAR/PAR2 GUI		* [http://www.hydrogenaudio.org/forums/index.php?showtopic=31146 HA Thread: "Parchive, subdirectory"]: A useful thread discussing PAR2 tactics
	*[http://www.dvdisaster.com/ dvdisaster] : Although not exactly PAR, dvdisaster uses the Reed-Solomon algorithm to create a correction file for a DVD image
	*[http://www.hydrogenaudio.org/forums/index.php?showtopic=31146 HA Thread : "Parchive, subdirectory"] : A useful thread discussing PAR2 tactics

Synthetic Soul: spelling

2006-03-17T15:31:31Z

spelling

← Older revision		Revision as of 15:31, 17 March 2006
Line 21:		Line 21:
	=PAR2=		=PAR2=

	PAR2 succeeded PAR; its main benefit being that there is no relationship between the size of the source files and the size of the PAR2 files, ''and'' that undamaged blocks in a corrupt PAR2 file can still be used to recover the recovery set. The [http://www.quickpar.org.uk/AboutPAR2.htm QuickPar] website has a good ~~desscription~~ of the main differences between the two formats.		PAR2 succeeded PAR; its main benefit being that there is no relationship between the size of the source files and the size of the PAR2 files, ''and'' that undamaged blocks in a corrupt PAR2 file can still be used to recover the recovery set. The [http://www.quickpar.org.uk/AboutPAR2.htm QuickPar] website has a good description of the main differences between the two formats.

	PAR2 files are named as follows:		PAR2 files are named as follows:

Synthetic Soul: Added to PAR2 section

2006-01-04T16:09:09Z

Added to PAR2 section

← Older revision		Revision as of 16:09, 4 January 2006
Line 1:		Line 1:
	PAR (''parity'') files are created from a source file or files (''recovery set''), and can be used to restore the recovery set if any file becomes corrupted.		PAR (''parity'') files are created from a source file or files (''recovery set''), and can be used to restore the recovery set if any file becomes corrupted.

	Many Hydrogen Audio members back-up their CD collection, and a good proportion of these archive their files using DVD. Optical media is prone to aging, and aging will lead to sector errors and file corruption. The use of PAR2 data can help you to restore a partially corrupted archive, allowing you the luxury of reburning the reconstructed files to a new disc. If you create parity data, and check your DVD archive regularly, there is no reason why you cannot continue this process ad infinitum, or at least until ~~DVDs~~ become obselete.		Many Hydrogen Audio members back-up their [[CD]] collection, and a good proportion of these archive their files using [[DVD]]. Optical media is prone to aging, and aging will lead to sector errors and file corruption. The use of PAR2 data can help you to restore a partially corrupted archive, allowing you the luxury of reburning the reconstructed files to a new disc. If you create parity data, and check your DVD archive regularly, there is no reason why you cannot continue this process ad infinitum, or at least until [[DVD]]s become obselete.


Line 10:		Line 10:
	PAR files are named as follows:		PAR files are named as follows:

	*.PAR		*filename.PAR
	*.P01		*filename.P01
	*.P02		*filename.P02
	*.P03		*filename.P03
	*etc.		*etc.

Line 25:		Line 25:
	PAR2 files are named as follows:		PAR2 files are named as follows:

	'''filename.vol<span style="color:red">nn</span>+<span style="color:purple">mm</span>.PAR2'''		* filename.PAR2
			* '''filename.vol<span style="color:red">nnn</span>+<span style="color:purple">mm</span>.PAR2'''
			**'''<span style="color:red">nnn</span>''' is the starting block number for this file, and the total number of blocks of all preceding files<br>
			**'''<span style="color:purple">mm</span>''' is the number of recovery blocks in this file, and therefore the number of blocks it can repair

	*'''<span style="color:red">nn</span>''' is the ~~total~~ number of ~~blocks of all preceding~~ files~~<br>~~
	*'''<span style="color:purple">mm</span>~~''' is the number~~ of blocks ~~in this file~~, ~~and therefore the number of~~ blocks ~~it can~~ repair		Therefore, if your recovery set becomes corrupt and your PAR2 client tells you that you need nine blocks to repair the set, you will need to utilise a number of PAR2 files whose <span style="color:purple">mm</span> values add up to nine, or more. This may be "filename.vol000+01.PAR2" and "filename.vol007+08.PAR2", or solely "filename.vol015+14.PAR2".

			Although you may create PAR2 files with a total of 200 recovery blocks, on repairing you only need to utilise those PAR2 files that contain enough blocks to repair the damage to your recovery set.

Synthetic Soul: /* Links */

2006-01-03T16:50:11Z

Links

← Older revision		Revision as of 16:50, 3 January 2006
Line 39:		Line 39:

	=Links=		=Links=

	~~==Tools==~~

	*[http://parchive.sourceforge.net/ Parchive: Parity Archive Tool] : Home of PAR		*[http://parchive.sourceforge.net/ Parchive: Parity Archive Tool] : Home of PAR
	*[http://www.quickpar.org.uk/ QuickPar] : A superb PAR/PAR2 GUI		*[http://www.quickpar.org.uk/ QuickPar] : A superb PAR/PAR2 GUI
	*[http://www.dvdisaster.com/ dvdisaster] : Although not exactly PAR, dvdisaster uses the Reed-Solomon algorithm to create a correction file for a DVD image		*[http://www.dvdisaster.com/ dvdisaster] : Although not exactly PAR, dvdisaster uses the Reed-Solomon algorithm to create a correction file for a DVD image
			*[http://www.hydrogenaudio.org/forums/index.php?showtopic=31146 HA Thread : "Parchive, subdirectory"] : A useful thread discussing PAR2 tactics
	~~==Related==~~

	*[http://www.hydrogenaudio.org/forums/index.php?showtopic=31146 Parchive, subdirectory] : A ~~good~~ thread discussing PAR2 tactics

Synthetic Soul at 16:48, 3 January 2006

2006-01-03T16:48:21Z

← Older revision		Revision as of 16:48, 3 January 2006
Line 1:		Line 1:
	PAR (''parity'') files are created from a source file or files (''recovery set''), and can be used to restore the recovery set if any file becomes corrupted.		PAR (''parity'') files are created from a source file or files (''recovery set''), and can be used to restore the recovery set if any file becomes corrupted.

			Many Hydrogen Audio members back-up their CD collection, and a good proportion of these archive their files using DVD. Optical media is prone to aging, and aging will lead to sector errors and file corruption. The use of PAR2 data can help you to restore a partially corrupted archive, allowing you the luxury of reburning the reconstructed files to a new disc. If you create parity data, and check your DVD archive regularly, there is no reason why you cannot continue this process ad infinitum, or at least until DVDs become obselete.


Line 36:		Line 38:


	=~~Useful~~ Links=		=Links=

			==Tools==

	*[http://parchive.sourceforge.net/ Parchive: Parity Archive Tool] : Home of PAR		*[http://parchive.sourceforge.net/ Parchive: Parity Archive Tool] : Home of PAR
	*[http://www.quickpar.org.uk/ QuickPar] : A superb PAR/PAR2 GUI		*[http://www.quickpar.org.uk/ QuickPar] : A superb PAR/PAR2 GUI
	*[http://www.dvdisaster.com/ dvdisaster] : Although not exactly PAR, dvdisaster uses the Reed-Solomon algorithm to create a correction file for a DVD image		*[http://www.dvdisaster.com/ dvdisaster] : Although not exactly PAR, dvdisaster uses the Reed-Solomon algorithm to create a correction file for a DVD image

			==Related==

			*[http://www.hydrogenaudio.org/forums/index.php?showtopic=31146 Parchive, subdirectory] : A good thread discussing PAR2 tactics

Synthetic Soul: Inital draft, more detail to come

2006-01-03T15:39:56Z

Inital draft, more detail to come

New page

PAR (''parity'') files are created from a source file or files (''recovery set''), and can be used to restore the recovery set if any file becomes corrupted.

=PAR=

PAR files were widespreadly used for Usenet newsgroup multi-part archive files. When posting a file a user could also post PAR files which would allow downloaders to recover any part of the archive by downloading an equal number of PAR files. I.e.: if two parts of the archive were missing or corrupt the downloader would just need to download ''any two'' PAR files and they could successfully recreate the archive.

PAR files are named as follows:

*.PAR
*.P01
*.P02
*.P03
*etc.

The .PAR file is simply a small (~1KiB) index file for the set, and does not contain any parity data.

=PAR2=

PAR2 succeeded PAR; its main benefit being that there is no relationship between the size of the source files and the size of the PAR2 files, ''and'' that undamaged blocks in a corrupt PAR2 file can still be used to recover the recovery set. The [http://www.quickpar.org.uk/AboutPAR2.htm QuickPar] website has a good desscription of the main differences between the two formats.

PAR2 files are named as follows:

'''filename.volnn+mm.PAR2'''

*'''nn''' is the total number of blocks of all preceding files 
*'''mm''' is the number of blocks in this file, and therefore the number of blocks it can repair

=How Does It Work?=

The redundant data in the PAR files is computed using the Reed-Solomon algorithm 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).

For more information read [http://parchive.sourceforge.net/docs/specifications/parity-volume-spec/article-spec.html the full PAR 2.0 specification].

=Useful Links=

*[http://parchive.sourceforge.net/ Parchive: Parity Archive Tool] : Home of PAR
*[http://www.quickpar.org.uk/ QuickPar] : A superb PAR/PAR2 GUI
*[http://www.dvdisaster.com/ dvdisaster] : Although not exactly PAR, dvdisaster uses the Reed-Solomon algorithm to create a correction file for a DVD image