Haven't found any posts on this bug, if I missed them then I apologize. Also should start off by thanking Sindre for this awesome software!
The Galaxy S phones have a large internal memory (14GB for users, 2GB for system) as well as the external microSD card.
The weird thing is that they chose to mount the user portion of the internal card at /sdcard and the external microSD at /sdcard/sd.
So even though I set my cache size to 500MB it doesn't stop it from putting more than 500MB in /sdcard/Subsonic (the internal 14GB).
I think what is happening is that Subsonic checks the remaining space left on /sdcard/sd (through some android API to the external card?) even though it is saving the files on a different storage space.
I'd suggest that for phones like this there should be an advanced setting to allow you to choose where to put the Subsonic cache (/sdcard/sd or /sdcard) and then apply the cache limits to the chosen filesystem.
cheers