@now2
Wow, I totally forgot about that path limit!
I never tried to backup a whole partition with lzx. I was only trying to archive 1 single game for Aminet (Total Chaos). This was way back in the 90's when the game was much smaller, probably 20 MB or less. And lzx just couldn't make a proper archive. It always corrupted some files. It is a bug that is triggered by having a dir with many files which are very very similar, maybe even a few that are identical. This always triggered the "corrupt archive" bug for me.
lha 1.x is highly reliable. You can't go wrong with it.
And be sure to install TLSFmem unless you want to wait 2 weeks for the backup to complete. I assume you are backing up 4 gigs or more?