We can see that when we try to create a sparse file a file under OS X (10.6) that the OS writes out the intervening pages.
KinMage:src thomas$ uname -a Darwin KinMage 10.6.0 Darwin Kernel Version 10.6.0: Wed Nov 10 18:13:17 PST 2010; root:xnu-1504.9.26~3/RELEASE_I386 i386 KinMage:src thomas$ python punch.py KinMage:src thomas$ ls -la p*out -rw-r--r-- 1 thomas staff 1023 Feb 13 21:44 p1023.out -rw-r--r-- 1 thomas staff 1024 Feb 13 21:44 p1024.out -rw-r--r-- 1 thomas staff 1025 Feb 13 21:44 p1025.out -rw-r--r-- 1 thomas staff 10250 Feb 13 21:44 p10250.out -rw-r--r-- 1 thomas staff 102500 Feb 13 21:44 p102500.out -rw-r--r-- 1 thomas staff 64 Feb 13 21:44 p64.out KinMage:src thomas$ du -sh p*out 4.0K p1023.out 4.0K p1024.out 4.0K p1025.out 12K p10250.out 104K p102500.out 4.0K p64.out
They should all be a multiple of a block size if there are sparse files. Since
they are not, we can conclude no sparse files were created.
Hmm, I wonder what happens over NFS?
