Right-click the selected files and choose Add to archive... from the menu.

rar a -p"yourpassword" pass80gbfromlogs.rar C:\path\to\your\logs Use code with caution. Copied to clipboard

Highlight the log files or the folder containing the 80GB of logs you want to compress.

(Optional) Check if you want to hide the names of the log files until the password is entered. Compression Settings: Select RAR as the archive format.

For large archives, it is highly recommended to add a Recovery Record (the -rr switch). This allows you to repair the archive if it gets slightly corrupted during a long download or transfer. RAR console version User's Manual - GitHub Gist