Low and High watermark purge is not working as documented

The documentation, at http://tinyurl.com/abuu9, states:

"Setting the Low and High Watermarks for Purging the File System Salvage

Purging begins for the file system salvage area when the volume's low watermark is reached and continues until its high watermark is reached. The default low watermark is when free space is 10% or less of the total disk space. The default high watermark is when free space is at least 20% of the total disk space."

That doesn't match how it behaves. In reality, when the volumes low watermark is reached, all that happens is that NSS stops salvaging newly deleted files, nothing else. It will not start to automatically purge old files until the volume is 100% full, and it has to purge to be able to save new files.
Low and High watermark purge is not working as documented