How to Reconstruct Missing RAR Volumes Using REV Files

When downloading or transferring multi-part RAR archives, volumes can become corrupted or go missing entirely. RAR addresses this through recovery volumes, which use the .rev file extension to reconstruct lost pieces of the split archive. This guide explains how to invoke the reconstruction process via the command line so you can regenerate your missing .rar files and extract your data without redownloading the entire set.

Understanding Recovery Volumes (.rev)

Recovery volumes allow you to restore missing parts of a split archive, provided you have at least as many .rev files as there are missing .rar files. For instance, if part03.rar and part07.rar are missing (two lost volumes), you will need any two .rev files (such as part01.rev and part02.rev) to rebuild them.

Reconstructing Missing Volumes

While unrar is primarily designed for decompression, reconstruction of recovery volumes is typically handled using the rc (ReConstruct) command provided by the RAR command-line utility. In some distributions, unrar supports this flag, but standard usage relies on the rar executable.

To rebuild missing volumes, navigate to the folder containing your files in your terminal and execute:

rar rc archive.part01.rev

(Replace archive.part01.rev with the filename of any single .rev file in your set.)

If your system uses a specialized build of unrar that includes the reconstruction module, the syntax is identical:

unrar rc archive.part01.rev

Step-by-Step Execution

  1. Verify Volume Counts: Ensure the number of available .rev files is equal to or greater than the count of missing .rar volumes.
  2. Target a Single File: You only need to run the command against a single .rev file. The utility will automatically scan the current directory to locate the other recovery files and determine which .rar parts need rebuilding.
  3. Wait for Generation: The program will compute the parity data and recreate the exact missing .partXX.rar files in your working directory.
  4. Extract the Archive: Once the missing pieces are restored, unpack the archive normally with:
unrar x archive.part01.rar

Automation Switches

If running the command inside an automated script, append the -y flag to assume "yes" to all interactive prompts:

rar rc -y archive.part01.rev