I just rejected a tag edit for "volume". Obviously this term is ambigeous so the tag should get a description now but a look at the questions with this tag showed me that most questions use it in the sense of filesystem volume, not in the sense of sound volume.
Thus I suggest to use it for filesystems.
Of course, there should be an additional tag for sound volume. But as I am not a native speaker I do not create that myself now but ask more qualified people to make suggestions.
volumemay be completely covered by the tagfilesystems.volumealone is too ambiguous, so isn't a good tag. As you correctly point out, it can be used for audio volume or filesystem volume, that's why I don't think it's a useful tag at all. If we want a tag for filesystem volumes, then I thinkfilesystem-volumewould be a better choice.