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RAR as an Incremental Backup Tool

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is a Windows version of the RAR archiver, the leading multiplatform archiver. There are several versions of RAR, for a number of OSes. Unpackers are avilable for free for most popular OSes.

While it is slow for backing up the whole partitions, RAR is a reasonably powerful and flexible incremental backup tool.  Rar also provides functionality for creating a 'solid' (tar style) archive, which can raise the compression ratio by 10% - 50% over more common methods, particularly when packing large numbers of small files which is the case for  many web sites archive 

WinRar offers both a classic interactive Windows interface and the command line interface. WinRar offers a number of backup service functions, such as setting a password, adding archive and file comments.

But what is the most important is that RAR has an excellent recovery capabilities. Even physically damaged archives may be repaired and an archive may be locked to prevent further changes. Authenticity information may be added for additional security.

Zip vs Rar

Incremental Back-ups based on modification time

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[Feb 6, 2007] Handling RAR and 7-Zip archives in Linux by Nathan Willis

February 01, 2007 ( )

... 7-Zip is a Windows application designed to handle as many compression formats as possible. Its native format is 7z, which uses a modern offshoot of the LZ77 compression algorithm. The 7-Zip Windows app and a 7z software development kit are available under the LGPL.

Both formats purport to achieve better compression ratios for common data types than older algorithms. They also support splitting large archives into multiple small volumes for easier mobility and error recovery. The combination of those two features had made them popular choices for online distribution of extremely large files such as ISO images.

7z and Linux

The 7-Zip app is open source, but remains Windows-only. For Linux users, the project links to a command-line client package named p7zip that provides two executables, 7z and 7za. The two have the same syntax and options, differing only in that 7za is a self-contained app compiled only for use with 7z and the essential Unix formats (tar, gzip, bzip2, etc.), while 7z uses a plugin architecture that allows it to support many additional compression formats.

The basic syntax is 7z function options filename.7z. To uncompress an archive, use 7z x myfile.7z . You can extract files from an archive with 7z e myotherfile.7z , but using the e function extracts all files to the current working directory, whereas x preserves their paths.

RAR and Linux

The RAR situation is a bit more complicated, due to the file format's proprietary compression scheme. The RARLAB site provides a no-charge proprietary uncompress-only client for Linux called unrar, designed for 32-bit Intel distros in both RPM and Slackware packages, and as standalone binaries for PowerPC, 64-bit Intel, and ARM Linux systems. Since RARLAB's unrar program is neither free software nor open source, you are unlikely to find it shipping with many Linux distributions. You can download a source code tarball from RARLAB, but the attached license explicitly forbids you from using the source code to develop any form of RAR encoder.

WinZip 9.0 printer friendly version

WinZip does not make much sense. WinRAR offers lifetime upgrades and compresses even better than ZIP, plus it handles more compression types than WinZip and opens ISO files.

(CNET Reviews) User comments

"Good software but doesn't support RAR format"

WinRAR on 29-Mar-2004 10:12:00 AM

Pros: If you work w/ a lot of zip files, having one of these utility can save time.

Cons: I use WinRAR instead because RAR compresses slightly better, and a lot of files I do come across are RAR files.

WinRAR archiver, a powerful tool to process RAR and ZIP files RAR - What's new in the Version 3.41

1. "Fastest" (-m1) RAR compression method has been modified to provide much higher compression speed and lower ratio. It may be useful for tasks requiring the high speed like regular backups. You may increase "Fastest" speed even more selecting 64KB compression dictionary instead of default 4MB.

2. WinRAR is able to decompress archives created by Unix 'compress' tool (.Z files). Like GZIP and BZIP2 archives, WinRAR opens tar.Z and .taz files in one step, so users do not need to unpack .tar manually.

3. WinRAR is able to decompress archives created by 7-Zip (.7z files). "Find" command is not supported for this archive type.

4. New "Security" dialog in WinRAR settings: a) "File types to exclude from extracting" option to prevent extracting of potentially dangerous files like .exe, .scr and .pif; b) "Propose to select virus scanner" option modifies behavior of "Scan archive for viruses" command. You may turn it off if you wish to skip the virus scanner selection dialog.

5. New command line switch -ep3 allows to save and restore full file paths including the drive letter.

WinRAR shell equivalent of -ep3 switch are options "Store full paths including drive letter" in "Files/File paths" page of archiving dialog and "Extract absolute paths" in "Advanced/File paths" page of extracting dialog.

6. You may select and compress disks directly in "My Computer" view in WinRAR shell. Just choose "My Computer" in WinRAR address bar, select disks to compress and press "Add". If you selected more than one item, WinRAR will automatically set "Store full paths including drive letter" archiving mode.

7. If you selected several disks in Windows Explorer "My Computer" view and started archiving from context menu, WinRAR will automatically set "Store full paths including drive letter" mode when compressing them.

8. New command line switch -oc to restore NTFS "Compressed" attribute when extracting files. RAR always saves "Compressed" attribute when creating an archive, but does not restore it unless -oc switch has been specified.

WinRAR shell equivalent of -oc switch is "Set attribute Compressed" option in "Advanced" part of extracting dialog.

9. Starting from this version RAR volumes contain the volume number field. If archive was created by WinRAR 3.40 or newer, you may view the volume number in the top line of "Info" dialog and in the address bar.

In the command line mode the volume number is displayed by 'L' and 'V' commands in the line with the total volume information.

This feature may be useful if original volume names are lost and you need to rename volumes to correct names.

10. Commands 'L' and 'V' display NTFS "Compressed" attribute in archive listing.

11. Switch -ag may include an optional text enclosed in '{' and '}' characters. This text is inserted into archive name. For example: -agHH{hours}MM{minutes}

Same feature is supported in "Generate archive name by mask" field of WinRAR archiving dialog.

12. If switch -ac is specified, RAR will not reset "Archive" attribute of those files, which size or modification time was changed after starting the archiving operation.

So files modified after placing them to archive and before clearing "Archive" attribute, will be included to next incremental backup. The same is true for WinRAR "Clear attribute "Archive" after compressing" GUI option.

13. If you use "Add to favorites" command inside of archive subfolder, WinRAR will save the subfolder and restore it when accessing to this favorite item. Previous versions were able to restore only the root archive folder.

14. When editing archived files, WinRAR proposes to update them immediately after detecting that file was changed. Previous versions waited until an external editor terminates before updating a changed file.

15. If you drop an archive to WinRAR address bar or toolbar, WinRAR will display its contents even if other archive is opened now. Previous versions proposed to add a dropped archive to browsing one.

You may still drop an archive to WinRAR file list if you need to add it to browsing archive.

16. Corrected processing of corrupt LZH archives to exclude a possible crash when reading corrupt LZH file headers.

17. RAR and WinRAR display the operation progress while repairing an archive containing the recovery record.

Version 3.30

1. New "Scan archive for viruses" command unpacks an archive to temporary folder and checks its contents with antivirus software installed on a user's computer.

2. New "Generate report" command creates a report containing the list of usual or archived files. You may optionally include a file size, date and CRC to report, choose the sort order, save report to file, send it to printer or copy to clipboard.

3. New "Benchmark and hardware test" command allows to compare performance of RAR compression algorithm on different computers and detect possible errors caused by hardware failures.

4. New "Print file" command is able to print both archived and usual files.

5. New "Tools" menu contains "Wizard", "Show information", "Convert archives", "Find files", "Repair", "Convert to SFX" commands previously available in "Commands" menu and new "Scan archive for viruses", "Generate report", "Benchmark and hardware test" commands.

6. WinRAR supports decompression of ZIP archives created using "Enhanced deflate" method.

7. WinRAR pre-allocates disk space for files unpacked from ZIP archives. It helps to reduce disk fragmentation, especially on NTFS disks. Previous versions did it only for RAR archives.

8. Now it is possible to decompress TAR, GZIP and ISO9660 archives of any size. Previous versions could not handle files of these formats, if they exceeded 2 GB.

9. Status bar displays the current operation progress, when reading contents of large tar.gz and tar.bz2 archives.

10. "Next volume" dialog allows to modify not only a name, but also a size of next volume, so you may create volumes of different size. This dialog is displayed if you create volumes on removable disks or set "Pause after each volume" option in "Advanced" part of archiving dialog.

11. Several -v switches can be specified in the command line mode to set different sizes for different volumes. For example, 'rar a -v100k -v200k -v300k arcname' command sets 100 KB size for first volume, 200KB for second and 300KB for all following volumes.

12. More WinRAR commands support Unicode in archive names. If your Windows is NT based (NT 4.0, 2000, XP, 2003), you may modify archives with non-English names regardless of Regional Settings.

13. Small and some of large icons have been updated by Francesco Indrio.

14. "Diagnostic message" window can be resized. It preserves new dimensions and restores them when activated the next time.

15. "Mode..." button in the archiving progress window allows to change the compression method and "Turn PC off when done" option on the fly.

16. WinRAR supports -cfg- switch in the command line mode. It forces WinRAR to ignore options saved in the default compression profile and RAR environment variable.

17. WinRAR opens .qpr and .qpk files (QNX packages) in one step, like it already does for .tar.gz archives.

18. Extraction command proposes to browse for missing CAB file in multivolume CAB sequence instead of "Cannot open" error.

19. "Rename" command displays a window with information about processing files.

20. "Convert" command checks the lowest allowed ratio before starting the archive test, so if resulting archive is too large, WinRAR does not waste time to test it.

21. "Files to exclude" field in the archiving dialog has "Append" button now, so you may browse for excluded files instead of entering their names manually.

22. WinRAR understands quotes inside of parameters in the command line mode. For example, "-pmy password" and -p"my password" will set the same password. Eariler WinRAR understood only the first syntax ("-pmy password") and only the console RAR handled both.

23. Data analyzing module is tuned to detect executable and audio data more accurately. Erroneous selecting of executable and audio algorithms could reduce the compression ratio in some situations.

24. WinRAR understands the command line switch -hp without a parameter and requests to enter a password when processing it.

25. WinRAR preserves NTFS streams of updated archives, if archive and temporary files are resided on NTFS partition. For example, if you entered some comments in "Summary" section of archive properties, they will not be lost when updating an archive using WinRAR. Do not confuse NTFS streams of archive itself and streams of archived files, latter can be preserved by previous versions as well.

26. It is possible to prohibit change of archiving password with "WinRAR\Policy\Password" Registry value. This feature may help to avoid encrypting of important data in multi-user environment. Read "Configuration settings/Registry variables" help topic for details.

27. "Select toolbar buttons" dialog allows to specify separators after any toolbar button.

28. New console RAR -si[name] switch to compress data from stdin (standard input).

29. Console RAR 'vt' and 'lt' commands display symlink target names, when listing RAR/Unix archives contained symbolic links. These commands also display NTFS stream names, when listing WinRAR archives contained streams.

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WinRAR archiver, a powerful tool to process RAR and ZIP files

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WinRAR (RARLab) 5

Needed. There's a reason so many people not only rely on, but absolutely love WinRAR - it works well and exceeds their expectations, especially in direct comparison to zip apps. What zip can't do, RAR can. Where zip gets unstable and flaky, RAR stands steady. Where zip sets limits, RAR has none. Slightly different than zip apps to learn, but easy to use. Best of all, I've never, ever had a RAR file fall corrupt or go bad on me in many years. Apart from being an excellent archive manager, WinRAR lets users compress and decompress RAR files. This "solid archive" format is able to compress files 10-50% more than other methods because it treats multiple files as a continuous stream of data. WinRAR also lets you create executables, self-extracting ZIP or RAR packets that do not require a compatible decompression program. Again, the options here are formidable and well-presented, so it is easy even for novices to do such things as customize the labels and messaging in the self-extraction interface, tweak file destination defaults, and set file overwriting policies. For those who prefer the RAR file format, clearly WinRAR is the program to get, but we were impressed by its sheer versatility and user-friendliness in unpacking most archival formats or even packing up files in the more common ZIP format. This is probably as much of a file extractor/compressor as you will ever need. WinRAR comes with a Lifetime license.

How to backup your data Guide by Mike Zelenczuk

Tools Integrated into Windows XP

Microsoft Windows XP has three main tools related to backing up your PC. The first I will address is System Restore. Basically what this feature is, is that you can set a "system restore point" on your computer at any time, and XP will take note of all your settings. If, in the future, you somehow manage to really screw up Windows to the point that it doesn't work properly anymore, you can activate System Restore so that your settings revert back to those at the time that you set your system restore point. This isn't really backing up files, but consider it to be backing up your Windows settings instead. It's usually a good idea to set a system restore point before you do anything that could potentially damage your OS. Access system restore from Start, Programs, Accessories, System Tools, System Restore.

XP's second tool I will tell you about is the Files and Settings Transfer Wizard. This is designed for backing up some of your Windows's settings and some of your files, so you can reinstall Windows and then continue with the same settings, and not lose all your files. However, I do not recommend backing up through this method because you end up wastefully copying your settings, some of which may be incorrect. Access the Files and Settings Transfer Wizard from Start, Programs, Accessories, System Tools, Files and Settings Transfer Wizard.

A final tool that XP offers is its backup program. By default this is not installed with your operating system, but if you dig around on your XP CD, you should be able to find the installer and load it. The backup program does a fine job of backing up your files, allowing you to select the files or folders you want to backup once, and then remembering these settings. However, I do not recommend this program for one reason. The program does not actually copy the original files, but copies them into one file of a format only the backup program can read, open and restore. So if you need to restore your files to a PC without the backup tool, you're screwed. If you have the backup program installed, access it from Start, Programs, Accessories, System Tools, Backup.

Using Batch Files

In my opinion, using batch files to backup your important files is the best way to go. It is likely not appropriate for the most beginner of users, however they are not too difficult to configure and once they are, they are extremely easy to use, and very low maintenance.

First off I should explain what a batch file is. A batch file is basically a mini-program that contains lines of code that are usually executed via the command line in DOS. (Don't worry if you don't understand what that means). Through batch files you can copy and move files, manipulate directories, and even execute programs if they offer command-line capabilities. When clicked, a batch file executes all the code that is contained in it. Batch files are created by typing the code in Notepad, and then saving the file with a .BAT extension. i.e. filename.bat.

The batch files that we will use for our backups generally include a command (which tells your PC what action to perform), directories (to tell your PC what files or folders to perform the action to), and switches, which are basically parameters for the command.

Don't worry if this all sounds daunting, its really quite simple. I have three batch files to make my backups (although they theoretically could be combined into one). The first copies all the files I want to backup onto my backup drive. The second uses the command line function in WinRAR to compress the files. The third deleted the copied files so that all I am left with is the compressed files.

In my first file I use the XCOPY command. This command is used to copy directories from one location to another. Its format is:

XCOPY "Drive:\From_Directory" "Drive:\To_Directory" /switches

A line from my own XCOPY batch file looks like this, as an example:

XCOPY "C:\Documents and settings\Owner\Desktop\SMCS 10" "G:\Backup\SMCS" /y/i/s

This means that it copies the folder "SMCS 10" from my desktop, to the Backup folder on my G drive. The "/y/i/s" are switches that change details in how the command is performed. For specific information on the switches and what they mean, as well as a general guide to the XCOPY command, look here.

In order to remove the directory after I RAR it, I use the RMDIR command, which removes directories. Mine simply looks like this:

RMDIR "G:\Backup" /s/q

That just means that the Backup folder on my G drive is deleted. A full reference to the RMDIR command can be found here.

In order to RAR my files, I needed to use code that is specific to the WinRAR program. In my case, it looks like this:

winrar a -r -M5 -MD4096 -Y -O+ -PMIKE -EP -ac -vn -ep1 -agDD-MMM-YY -df "G:\backup.rar" "G:\Backup"

Although it seems confusing, all it is really saying is that my backup folder is compressed to backup.rar. The switches have various effects, such as naming the file based on the date, and setting a password for it. Note that the batch file must be placed in the WinRAR folder in order to properly execute the program. Here is a more specific guide on using WinRAR through the command line.

As I stated previously, the commands in a batch file are executed once the file is clicked. Therefore, I can copy, RAR, and clean up my files in three clicks. But what makes batch files even more useful are using them through Scheduled Tasks.

With Windows' Scheduled Tasks, you can set pretty much any program to start automatically at a specific time or date, dependant on what you set. So, you can set your batch files to run, for example, every Saturday at 9:00pm, and then you won't have to worry about backing up your files – it will be done for you. Scheduled Tasks are accessible from Start, Programs, Accessories, System Tools, Scheduled Tasks.

I realize that all these concepts involving batch files can be quite confusing, so feel free to email me if you are having any problems, and I will try my best to help you.

Tutorial - General - RAR-SFV-NFO

RAR Files

Many people are confused by RAR files and do not know how they truly work. They are quite simple and very similar to the common zip file. The big difference is the compression method they use, usually a file can be compressed smaller using RAR than if ZIP was used. Also when creating RAR files it is easy to make them into multiple sections. The purpose of this is to make downloading easier, and if you get a corrupt file you only have to download a small chunk and not a huge 500+ MB file. Standard split RAR files start out with the .rar extension then go to numbers starting with .r00, .r01, etc. The main file is the .rar and is where the whole archive begins. You do not even need all of the files to extract smaller files in the archive. If you have each piece with the information for a file you can extract it. With big releases the case usually is that there is only 2 files and you need both so you must acquire all the pieces of the RAR file. Sometime certain groups will not use the standard naming scheme for the files, but instead use the extensions .001, .002, .etc. Here the main file is .001 and everything is pretty much the same, but with different file extensions. This is probably done to conceal what the files really are.

If you are having problems seeing all the file extensions you may have file extension hiding turned on in windows. To disable this annoying option in WindowsXP open up Windows Explorer (WindowsKey + E) go to Tools -> Folder Options and switch to the "View" tab and uncheck "Hide extensions for known file types". For any other version of windows it should be almost the same, just look in the folder options and you should find it.

Ok now that you know a little about RAR files its time to install WinRAR. Just run the installer and let it do its thing. All the default settings should be good for now, you can play with them later. WinRAR should automatically install shell extensions which make it easy to extract the .rar files. If you have a full set of RAR files with the normal file extensions you can now right click on the .rar file and select WinRAR -> "Extract to <filename>\". This will extract the contents of the whole set of RARs into a subfolder named after the file. If you have a set of RARs without the standard file extensions the shell menu will not appear. To extract these you need to open WinRAR and use its built in file browser to browse to the folder with the files. Select the first file in the set (usually .001) and click the "Extract To" Button. It will come up with a dialog box showing the folder it will extract to and some other options. It automatically generates a subfolder to extract to based on the filename so you can just press ok to extract it there.

*NOTE: If you have checked all the files with a SFV and they are fine but WinRAR is giving CRC errors, make sure you have the newest version of WinRAR. Sometimes with a new version they will update the compression method, and the older versions wont be able to handle it.

That's it, you should now have your files extracted and ready to use. If you end up with a BIN and CUE file you need to burn it or virtually mount it to use it.

Soulmaniacs - WinRAR Tutorial



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