mirror of
https://github.com/Ponce/slackbuilds
synced 2024-12-01 01:00:03 +01:00
284 lines
9.2 KiB
Groff
284 lines
9.2 KiB
Groff
.\"
|
|
.\" par2(1)
|
|
.\"
|
|
.\" Copyright (C) 2004 Andres Salomon
|
|
.TH par2 1 "May 2004"
|
|
.SH NAME
|
|
par2 \- PAR 2.0 compatible file verification and repair tool.
|
|
.SH SYNOPSIS
|
|
.B par2
|
|
c(reate) [options] <par2 file> [files]
|
|
.br
|
|
.B par2
|
|
v(erify) [options] <par2 file> [files]
|
|
.br
|
|
.B par2
|
|
r(epair) [options] <par2 file> [files]
|
|
.br
|
|
|
|
.br
|
|
Or:
|
|
.br
|
|
|
|
.br
|
|
.B par2create
|
|
[options] <par2 file> [files]
|
|
.br
|
|
.B par2verify
|
|
[options] <par2 file> [files]
|
|
.br
|
|
.B par2repair
|
|
[options] <par2 file> [files]
|
|
.SH DESCRIPTION
|
|
par2 is a program for creating and using PAR2 files to detect
|
|
damage in data files and repair them if necessary. It can be used with
|
|
any kind of file.
|
|
.SH OPTIONS
|
|
.TP
|
|
.B -b<n>
|
|
Set the Block-Count
|
|
.TP
|
|
.B -s<n>
|
|
Set the Block-Size (Don't use both -b and -s)
|
|
.TP
|
|
.B -r<n>
|
|
Level of Redundancy (%)
|
|
.TP
|
|
.B -c<n>
|
|
Recovery block count (don't use both -r and -c)
|
|
.TP
|
|
.B -f<n>
|
|
First Recovery-Block-Number
|
|
.TP
|
|
.B -u
|
|
Uniform recovery file sizes
|
|
.TP
|
|
.B -l
|
|
Limit size of recovery files (Don't use both -u and -l)
|
|
.TP
|
|
.B -n<n>
|
|
Number of recovery files (Don't use both -n and -l)
|
|
.TP
|
|
.B -m<n>
|
|
Memory (in MB) to use
|
|
.TP
|
|
.B -v [-v]
|
|
Be more verbose
|
|
.TP
|
|
.B -q [-q]
|
|
Be more quiet (-qq gives silence)
|
|
.TP
|
|
.B --
|
|
Treat all remaining CommandLine as filenames
|
|
.TP
|
|
.BR
|
|
.SH EXAMPLES
|
|
|
|
With PAR 2.0 you can create PAR2 recovery files for as few as 1 or as many as
|
|
32768 files. If you wanted to create PAR1 recovery files for a single file
|
|
you are forced to split the file into muliple parts and RAR is frequently
|
|
used for this purpose. You do NOT need to split files with PAR 2.0.
|
|
|
|
To create PAR 2 recovery files for a single data file (e.g. one called
|
|
test.mpg), you can use the following command:
|
|
|
|
par2 create test.mpg
|
|
|
|
If test.mpg is an 800 MB file, then this will create a total of 8 PAR2 files
|
|
with the following filenames (taking roughly 6 minutes on a PC with a
|
|
1500MHz CPU):
|
|
|
|
test.mpg.par2 - This is an index file for verification only
|
|
test.mpg.vol00+01.par2 - Recovery file with 1 recovery block
|
|
test.mpg.vol01+02.par2 - Recovery file with 2 recovery blocks
|
|
test.mpg.vol03+04.par2 - Recovery file with 4 recovery blocks
|
|
test.mpg.vol07+08.par2 - Recovery file with 8 recovery blocks
|
|
test.mpg.vol15+16.par2 - Recovery file with 16 recovery blocks
|
|
test.mpg.vol31+32.par2 - Recovery file with 32 recovery blocks
|
|
test.mpg.vol63+37.par2 - Recovery file with 37 recovery blocks
|
|
|
|
The test.mpg.par2 file is 39 KB in size and the other files vary in size from
|
|
443 KB to 15 MB.
|
|
|
|
These par2 files will enable the recovery of up to 100 errors totalling 40 MB
|
|
of lost or damaged data from the original test.mpg file when it and the par2
|
|
files are posted on UseNet.
|
|
|
|
When posting on UseNet it is recommended that you use the "-s" option to set
|
|
a blocksize that is equal to the Article size that you will use to post the
|
|
data file. If you wanted to post the test.mpg file using an article size
|
|
of 300 KB then the command you would type is:
|
|
|
|
par2 create -s307200 test.mpg
|
|
|
|
This will create 9 PAR2 files instead of 8, and they will be capable of
|
|
correcting up to 134 errors totalling 40 MB. It will take roughly 8 minutes
|
|
to create the recovery files this time.
|
|
|
|
In both of these two examples, the total quantity of recovery data created
|
|
was 40 MB (which is 5% of 800 MB). If you wish to create a greater or lesser
|
|
quantity of recovery data, you can use the "-r" option.
|
|
|
|
To create 10% recovery data instead of the default of 5% and also to use a
|
|
block size of 300 KB, you would use the following command:
|
|
|
|
par2 create -s307200 -r10 test.mpg
|
|
|
|
This would also create 9 PAR2 files, but they would be able to correct up to
|
|
269 errors totalling 80 MB. Since twice as much recovery data is created, it
|
|
will take about 16 minutes to do so with a 1500MHz CPU.
|
|
|
|
The "-u" and "-n" options can be used to control exactly how many recovery
|
|
files are created and how the recovery blocks are distributed amoungst them.
|
|
They do not affect the total quantity of recovery data created.
|
|
|
|
The "-f" option is used when you create additional recovery data.
|
|
|
|
e.g. If you have already created 10% and want another 5% then you migh use
|
|
the following command:
|
|
|
|
par2 create -s307200 -r5 -f300 test.mpg
|
|
|
|
This specifies the same block size (which is a requirement for additional
|
|
recovery files), 5% recovery data, and a first block number of 300.
|
|
|
|
The "-m" option controls how much memory par2 uses. It defaults to
|
|
16 MB unless you override it.
|
|
|
|
CREATING PAR2 FILES FOR MULTIPLE DATA FILES
|
|
|
|
When creating PAR2 recovery files form multiple data files, you must specify
|
|
the base filename to use for the par2 files and the names of all of the data
|
|
files.
|
|
|
|
If test.mpg had been split into multiple RAR files, then you could use:
|
|
|
|
par2 create test.mpg.rar.par2 test.mpg.part*.rar
|
|
|
|
The files filename "test.mpg.rar.par2" says what you want the par2 files to
|
|
be called and "test.mpg.part*.rar" should select all of the RAR files.
|
|
|
|
VERIFYING AND REPAIRING
|
|
|
|
When using par2 recovery files to verify or repair the data files from
|
|
which they were created, you only need to specify the filename of one
|
|
of the par2 files to par2.
|
|
|
|
e.g.:
|
|
|
|
par2 verify test.mpg.par2
|
|
|
|
This tells par2 to use the information in test.mpg.par2 to verify the
|
|
data files.
|
|
|
|
par2 will automatically search for the other par2 files that were
|
|
created and use the information they contain to determine the filenames
|
|
of the original data files and then to verify them.
|
|
|
|
If all of the data files are ok, then par2 will report that repair
|
|
will not be required.
|
|
|
|
If any of the data files are missing or damaged, par2 will report
|
|
the details of what it has found. If the recovery files contain enough
|
|
recovery blocks to repair the damage, you will be told that repair is
|
|
possible. Otherwise you will be told exactly how many recovery blocks
|
|
will be required in order to repair.
|
|
|
|
To carry out a repair use the following command:
|
|
|
|
par2 repair test.mpg.par2
|
|
|
|
This tells par2 to verify and if possible repair any damaged or
|
|
missing files. If a repair is carried out, then each file which is
|
|
repaired will be re-verified to confirm that the repair was successful.
|
|
|
|
MISSNAMED AND INCOMPLETE DATA FILES
|
|
|
|
If any of the recovery files or data files have the wrong filename, then
|
|
par2 will not automatically find and scan them.
|
|
|
|
To have par2 scan such files, you must include them on the command
|
|
line when attempting to verify or repair.
|
|
|
|
e.g.:
|
|
|
|
par2 r test.mpg.par2 other.mpg
|
|
|
|
This tells par2 to scan the file called other.mpg to see if it
|
|
contains any data belonging to the original data files.
|
|
|
|
If one of the extra files specified in this way is an exact match
|
|
for a data file, then the repair process will rename the file so that
|
|
it has the correct filename.
|
|
|
|
Because par2 is designed to be able to find good data within a
|
|
damaged file, it can do the same with incomplete files downloaded from
|
|
UseNet. If some of the articles for a file are missing, you should still
|
|
download the file and save it to disk for par2 to scan. If you
|
|
do this then you may find that you can carry out a repair in a situation
|
|
where you would not otherwise have sufficient recovery data.
|
|
|
|
You can have par2 scan all files that are in the current directory
|
|
using a command such as:
|
|
|
|
par2 r test.mpg.par2 *
|
|
|
|
WHAT TO DO WHEN YOU ARE TOLD YOU NEED MORE RECOVERY BLOCKS
|
|
|
|
If par2 determines that any of the data files are damaged or
|
|
missing and finds that there is insufficient recovery data to effect
|
|
a repair, you will be told that you need a certain number of recovery
|
|
blocks. You can obtain these by downloading additional recovery files.
|
|
|
|
In order to make things easy, par2 files have filenames that tell you
|
|
exactly how many recovery blocks each one contains.
|
|
|
|
Assuming that the following command was used to create recovery data:
|
|
|
|
par2 c -b1000 -r5 test.mpg
|
|
|
|
Then the recovery files that are created would be called:
|
|
|
|
test.mpg.par2
|
|
test.mpg.vol00+01.par2
|
|
test.mpg.vol01+02.par2
|
|
test.mpg.vol03+04.par2
|
|
test.mpg.vol07+08.par2
|
|
test.mpg.vol15+16.par2
|
|
test.mpg.vol31+19.par2
|
|
|
|
The first file in this list does not contain any recovery data, it only
|
|
contains information sufficient to verify the data files.
|
|
|
|
Each of the other files contains a different number of recovery blocks.
|
|
The number after the '+' sign is the number of recovery blocks and the
|
|
number preceding the '+' sign is the block number of the first recovery
|
|
block in that file.
|
|
|
|
If par2 told you that you needed 10 recovery blocks, then you would
|
|
need "test.mpg.vol01+02.par2" and "test.mpg.vol07+08.par". You might of course
|
|
choose to fetch "test.mpg.vol15+16.par2" instead (in which case you would have
|
|
an extra 6 recovery blocks which would not be used for the repair).
|
|
|
|
.SH NOTES
|
|
|
|
This version of par2 does not support recording path information for
|
|
files. Whilst you can create recovery files for files from multiple locations,
|
|
it will expect all files to be in the current directory when verifying and
|
|
repairing. This limitation will be corrected in an update.
|
|
|
|
.SH REED SOLOMON CODING
|
|
|
|
PAR2 uses Reed Solomon Coding to perform its calculations. For details of this
|
|
coding technique try the following link:
|
|
|
|
``A Tutorial on Reed-Solomon Coding for Fault-Tolerance in RAID-like Systems''
|
|
<http://www.cs.utk.edu/~plank/plank/papers/CS-96-332.html>
|
|
|
|
.SH AUTHOR
|
|
.br
|
|
.B par2
|
|
was written by Peter Brian Clements <peterbclements@users.sourceforge.net>.
|
|
|
|
This man page was contributed by Andres Salomon <dilinger@voxel.net>
|
|
for the Debian GNU/Linux system (but may be used by others).
|