-ms=2g : Limits solid blocks to 2GB to balance compression and access speed. 7z(1) — p7zip-full — Debian stretch
-ms=off : Disables solid mode for faster individual file access. backup.7z
The "solid" feature in a file refers to Solid Compression , a method where 7-Zip treats multiple files as a single continuous data block. -ms=2g : Limits solid blocks to 2GB to