What is RAR file extension (original) (raw)

What are RAR files, WinRar archive format

RAR file extension

RAR extension designates a popular archive format introduced by RarLab's program WinRAR (shareware file archiving utility, free for 40 days) for Microsoft Windows platform; the software was ported to Linux (only as extractor) by the same Author, Eugene Roshal. Initial application release dates back to 1995, last RAR5 standard revision is from 2013.

PeaZip free archiver features read support to open and extract RAR filesthrough Open Source unrar components from 7z/p7zip, and can convert existing .rar archives into any write supported archive format, providing an Open Source alternative to WinRar for extraction of rar archives.
Also, PeaZip can create RAR filesthrough WinRar if available on the machine - autonomous support to rar compression is not possible due to RarLab's rar format licensing limitations.
Optionally, the program allows managing RAR5 file type with separate UNRAR / UNRAR5 Plugin based on RarLab's unrar code - not mandatory, PeaZip can natively handle RAR5 standard out of the box.

RAR format specs

RAR file format features

RAR format was designed ground up to avoid practical limitations in terms of size and number of items in archive:

RAR format is well known for the high compression ratio - superior compared to zip, comparable with 7z format and zipx format - being the compressor based on Lempel-Ziv (LZSS) algorithm and prediction by partial matching (PPMd, Dmitry Shkarin).

RAR standard also features strong file encryption by design

encrypted RAR4 archives rely on AES-128 based encryption
encrypted RAR5 archives rely on AES-256 in CBC mode, with improved key scheduling, and can optionally use cryptographically strong 256-bit BLAKE2sp hash instead of CRC32 checksum to verify integrity of files inside archives

Error correction in RAR file format

Notably, .rar format features advanced error correction / data recovery capabilities setting optional recovery records during archive creation (from WinRar).

Extension for RAR4 and RAR5 file types
Please note RAR4 and RAR5 standard revisions both have same .rar extension, the format revision level being declared in file header area.

R01 file extension
Spanned multi-volume rar archives are designed by R01 extension - with file extension numerator incremented for following volumes of the set.

Maximum size of a RAR archive

RAR file can be large up to 2^63 bytes in size (8 exabytes of total size of the archive, signed 64 bit integer of filesize field), far exceeding current needs and capabilities of most filesystems.
To work with input files, or output archives, larger than 4 GB, FAT32 filesystem should be avoided (limited to files smaller than 2^32 bytes).
Both NTFS and exFATfilesystems allows maximum file size up to 2^64 byte (16 exabyte), large enough to accomodate largest possible rar format file size - theoretically, as current implementations are limited to smaller max file sizes.

Maximum number of files in a RAR archive

RAR file can contain up to 2^31 files (max 2 billion files, signed 32 bit integer for file number filed), which makes rar format suitable for archiving large number of files and directories, especially if compared to competing early ZIP standard limited to 64K maximum files (2^16).
Online resources about rar file type: WinRar winrar file type official domain, RAR format rar file format Wikipedia entry, what is error correction RAR recovery records , 7-Zip open source rar

No Open Source RAR implementation (with full read / write support) is consequently known to be able to fully replace WinRar. Anyway PeaZip can write to RAR format (create new rar archives, and edit existing archives - add, delete, update) using WinRar executable, if installed, without leaving the application - this works simply setting Rar.exe as custom compressor utility in PeaZip.

Synopsis: What is RAR format. What are .rar archives, native WinRar archive type, specs. What are rar file type limitations in terms of maximum archive size, max number of items in archive and max size of file in archive. RAR file format specifications, features and advantages for compression ratio, and advanced features such recovery records and AES encryption.

Topics: rar file extension specs

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