tino.schwarze@xxxxxxxxxxxxxxxxxxxxxxxxx (2003-08-15 at 1541.28 +0200): > BTW: Would it be possible to get a sparse file by zeroing the unused > bits? Then it would be quite space efficient (at least with some file > systems). Yes, try it with dd and cp (GNU version only?): dd if=/dev/zero of=/tmp/zero-test count=1000 cp --sparse=always /tmp/zero-test /tmp/zero-sparse ls -l /tmp/zero-test /tmp/zero-sparse du -cs /tmp/zero-test /tmp/zero-sparse If you get same byte size, 512000 bytes, but different block usage, 0 vs 503 here, your fs is doing sparse files. Another test I did here with a 8258506 bytes file, composed by catting a real data file of 7745389 bytes, then 512000 zero bytes and a final 1117 byte group of random data, gives an usage of 8098 blocks for the original and 7601 for the sparse copy. What I do not know is how many fs support it, and if they can do on the fly or a forced copy is needed, or if it is a good idea from performance point of view. GSR
