What are sparse files and how to deal with them?

Question

When dealing with sparse files, df appears to report the dummy size and not the apparent size of the file which makes it difficult to monitor free space on the system. (I use df -h to check disk usage). How do I deal with these sparse files? If not df then what would be the ideal way to check disk usage?

Answer 1

df doesn't report a dummy size but the actual disk space taken by sparse (and non sparse) files. There is no particular reason to monitor/compute the disk usage otherwise.