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Re: SPARSE files considered harmful - please revert

Martin Buchholz wrote:
> As a result, a non-empty but small sparse file takes up a minimum of
> 16*clustersize bytes on the disk.  My measurements suggest an overhead
> of 32kb per file with a cluster size of 4kb.

I just thought I'd throw a few more numbers into the debate:

I patched Cygwin to respond to CYGWIN=sparse / CYGWIN=nosparse
Then, I did a cvs co winsup:

"Size on disc" of checked out dir, as shown in Windows properties box:
Sparse: 40.7MB
Not sparse: 43.6MB
OK, so sparse seems to win? But that makes no sense - backed up by noting
that for various individual sparse files, "Size on disc" is reporting a size
which is not an integer number of clusters.

Now, Properties of disc, look at "Used space":
Difference in creating sparse checkout: ~ 200MB !!!
Difference in creating normal checkout: ~  40MB

Personally, I'm inclined to trust the overall disc stats more.

I think this evidence suggests that sparse files should NOT be on by default
in Cygwin.


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