You don't need to backup an 80 gig partition; you only need to backup the files in that partition.
Method 1) make a tar archive of the partition, compress it with gzip or bzip2, and store it in another partition or on another drive. If reinstallation is necessary, install a minimal system, then restore the backup.
Drawback: tar makes a monolithic archive. If any part is corrupt, you risk loosing the entire archive.
Method 2) use dar to backup the files. Unlike tar, dar archives each file individually. If any part of the backup is corrupt, you only risk loosing the corrupt file. Dar has a skip-ahead feature. In some cases, that feature can skip-ahead over the corrupt portion of a file and continue the restoration. Hopefully, you have other means to restore the corrupt portion. If dar cannot restore a file, it gives an error message which file couldn't be restored. If it's a binary, at least you know which application has to be re-installed to regain functionality.
If reinstallation of the OS is necessary, install a minimal system, install dar, and restore your backup. If you have written backup and restore scripts for dar, it's easy to extract them from the backup in order to use them in the restoration.
Dar also includes a static version of dar which runs as a stand-alone application which can also be extracted and used to effect restoration.
Dar includes a good step-by-step tutorial which can be used to write your backup and restore scripts (bash shell scripts).
Drawback: it takes a while to practice with the tutorial and write your backup and restore scripts.
There are probably other equally useful backup applications. I've tried several, and finally settled on dar because it give me what I want.