(I posted this first on serverfault, but then I realized it probably belongs here.)
I'm trying compress a very large text file using 7za (p7zip) 9.20. The -mmt option doesn't seem to have any effect. I've tried both -mmt=on and -mmt=2. This is an 8-core machine. One person suggested adding -m0=lzma2 as an argument, but that just gives me E_INVALIDARG. Does anybody know how to make this work?
This has no effect:
7za a -mx=9 -mmt=2 -p myarchive.zip bigfile.txt
And this fails with an error:
7za a -m0=lzma2 -mx=9 -mmt=2 -p myarchive.zip bigfile.txt 7-Zip (A)  9.20 Copyright (c) 1999-2010 Igor Pavlov 2010-11-18 p7zip Version 9.20 (locale=en_US.UTF-8,Utf16=on,HugeFiles=on,8 CPUs) Scanning Creating archive release_20120601-1-http.zip System error: E_INVALIDARG