5-Extract and UnRAR Files

Step 5 has the following sections:

Introduction to Extract/UnRAR Files
NFO and SFV Files
WinRAR RAR Sets
Repair Damaged and Missing Segments
PAR Files
REV Files

See Figure 1 which is referred to throughout this tutorial.

Introduction to Extract/UnRAR Files Top

Most large files are posted to a usenet group in chunks which are created using WinRAR. WinRAR is a compression program similar to the more commonly known WinZip. After downloading a set of RAR files you need to put them together into a file that you can use.

Decompressing the parts and reconstituting the original file is pretty straightforward. Once you have all the parts the decompression software pretty much does its job automatically.

However, if any of the RAR files is damaged or missing segments you need to either get replacements or repair (or recover) them before you can proceed further.

Read the NFO file and use the SFV file that accompanied the post to find out what files you need, and what you need to do to replace or recover missing or damaged parts.

NFO and SFV Files Top

These files are your instructions to help you determine what or how many parts make up a movie, TV program or other file post. READ THEM FIRST!

NFO Files

Before asking for reposts and asking questions READ THE NFO FIRST!
They are usually posted first, before all the parts of the post.
NFO is short fo "info" (get it ... info without the i).
Contain instructions on how you can recover files or get reposts.
Indicate size and number of parts in the file post.
You can open an NFO file using Windows Notepad (it is just a text document) you can just change the file extension to .txt. WinRAR also has a built-in viewer.

SFV Files

They are usually posted first, before all the parts of the post.
Are an index of the posted files and can be used to check the RAR sets for integrity using, amongst other programs, WinSFV.
You can open an SFV file using Windows Notepad (it is just a text document) to quickly check of the number of parts and their size.
With the more recent frequent use of PAR files, SFV files are becoming redundant in terms of their use as an archive checker.

WinRAR RAR Sets Top

Referring to Figure 1, the parts are usually RARs created by WinRAR.

WinRAR creates a set of files of equal size with a smaller last file which basically contains the "left-overs".

This set of RAR files will be numbered sequentially. The first file in a RAR set ends with .rar and the following RAR files are numbered sequentially beginning with the second RAR file in the set is .01, the third RAR file is .02, etc as illustrated below:

1st file in set: filename.rar - 10 MB
2nd file in set: filename.r01 - 10 MB
3rd file in set: filename.r02 - 10 MB
4th file in set: filename.r03 - 10 MB
Last file in set: filename r.04 - 9.5 MB

Occassionally, the RAR file extension numbering is different. For example, the RAR set could start with filename.r00 instead of filename.rar. Don't worry, it will work just the same. You simply need a complete set of files in order to reconstitute the original file. The nfo file or sfv file posted will list the entire set of RARs posted.

To extract the file from the RAR set, you simply doubleclick on any of the RAR files and follow WinRAR's instructions. Alternatively, you can open WinRAR, and then open the folder with all the RARs and select them all and click Extract. It is very easy. If you encounter any errors it is likely that the RAR set has corrupt RARs which have damaged or missing segments.

Use PAR files or .rev files or WinRAR file repair to recover missing RARs and repair those RARs with missing or damaged segments (see below).

Repair Damaged and Missing Segments Top

If any of the segments for a RAR file in a RAR set are missing or damaged you will not be able to extract the file inside. As discussed in the previous Step 4: Download from Usenet there are any number of reasons why a posted file may have damaged or missing segments.

There are three ways to get replacements for missing or damaged messages:

Wait Patiently - Waiting patiently for the poster to finish his post or for the news server to get all the segments.
Ask for Repost - Asking the poster to repost just the missing or damaged segments. Often, somebody will nicely repost the whole movie or episode. Just wait a day or two.
Sign-up with one of the popular Newsgroup Service Providers - if your ISP's newsgroups don't have any usenet groups or have poor retention buy Usenet access from Affiliate goes here, a popular news service provider.

There are two ways of recovering missing or damaged messages:

PAR, PAR2 & PAR3files - are a godsend. After a set of RAR's or files are created, the poster creates a second set of files called PAR files that contains information that can help recover missing files. See below.
WinRAR Repair Feature - WinRAR has a feature to recover damaged or missing RAR's however, the poster has to include a recovery record with his set of RAR's. See below.

PAR Files Home - Top

PAR is short for PARity Volume Set. Essentially, PAR files are used to verify that a set of files are not corrupt and reconstruct the set of files providing that enough PAR files have been provided. The primary intention of the Parity Volume Set is to eliminate some repost requests in usenet groups.

First there was PAR, now there is PAR2 and PAR3. They all serve the same purpose, ie veryifying and recovering lost and damaged files but there are some significant differences in the way they do this. You can read more about these differences at sourceforge.net.

The basic concept for using PAR files follows.

For example, someone posts 10 RAR volumes to a group. But for a variety of reasons not everyone gets all of them. One person may be missing r01, another missing r06 and a third person is missing r04.
Usually, these three people would each have to ask for reposts of the missing files. But using PAR, the poster would create a parity volume set based on the 10 original RAR files which is posted along with the RARs.
Then the each person who is missing RAR files can download the PAR file and use it to recover the missing file(s) that they need ie, one PAR set posted can be used by all three people to reconstruct different missing files, as required.
The benefit is that a one-time post of a PAR file set eliminates the need to repost 3 RAR's.

PAR software:

QuickPAR- http://www.quickpar.org.uk/index.php