Hi Gary and Larry,
Thank you for your comments, replies below:
On Wednesday 02 August 2006 7:08 pm, you wrote:
> > Any suggestions and comments would be greatly
> > appreciated.
> > Please CC me - I am not on the list.
> >
> > thank you very much
> >
> > Vladimir Dergachev
>
> I'll try your test case when I get a chance, but my WAG is that you're
> seeing the effects of Cygwin's creation of sparse files by default for any
> file beyond a certain size. I unfortunately do not recall what that size
> is. What happens as you change FILE_SIZE and/or BUFFER_SIZE in your
> script, to maybe a small multiple of your cluster size?
I tried buffer_size of 10K, 100K, 1M and 10M - no big difference, except a
small decrease in number of fragments for 10M value - could be noise..
I also tried a smaller file size - 3M, the number of fragments decreased to
33, roughly proportionally to size.
Unfortunately, I do not know what cluster size is.
With regard to sparse files the intent here is to open a file, write data to
it and the close. No seeks involved, much less void regions. I do understand
that internally cygwin could do something different.
I have not found a utility to identify a sparse file yet - if you happen to
have a link I would greatly appreciate it.
Also, I tried the following experiment - found a 17 MB file in ibiblio.org and
downloaded it with FireFox. The file ended up fragmented into more than 200
pieces. Tried the same file with IE - no fragmentation.
It could be, of course, that Firefox is compiled with cygwin, but I have not
found cygwin.dll anywhere in its installation directory.
thank you
Vladimir Dergachev
PS I'll try writing a C program when time permits - any suggestions on what
API besides regular open/write/close to use ?
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