[mythtv-users] Storage group extra disk space clarification

[faginbagin]

I'd like to clarify the definition of the "Extra Disk Space" configuration option in mythfrontend Setup - TV Settings - General (AutoExpire) page on 0.23.1. The help text says:
Extra disk space (in Gigabytes) that you want to keep free on the recording file systems beyond what MythTV requires.

Maybe that should be 100% clear, but given the nature of the English language and the games played by HD manufacturers, I'm confused. Here are my questions:

1) Is a Gigabyte = 1000*1000*1000 bytes (according to HD manufacturers) or 1024*1024*1024 bytes (aka a GiB)?

2) Is the extra free space per file system or per storage group? IOW, if I've got two file systems defined for my default storage group and I'd like to make sure at least one of those file systems has 40 gigabytes free, should I set this value to 40 or to 80?

TIA,
Helen