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Re: SPARSE files considered harmful - please revert
Christopher Faylor wrote:
On Mon, May 19, 2003 at 07:27:06PM -0400, Bill C. Riemers wrote:A agree that he is making an assumption, but he is probably right. Even
if 16 blocks are reserved for adding intermediate blocks, you would
still end up with out-of-order blocks in the file; which isn't as bad as
real fragmentation, but isn't as good as all blocks in order.
I think you need to read the documentation a little more closely. Either that
or provide references to the parts of the documentation that says that
normal RW operations would fragment a sparse file.
It is rather obvious. Let say you have three blocks worth of data, and
is written into a file with a physical block followed by a sparse block
followed by a physical block. No disk space is reserved for the sparse
block. Why should it be, as it would defeat the whole purpose of using
sparse files? So physically on disk you have two consecutive physical
blocks. What then happens if you open the file in RW mode, seek to the
sparse block and write some data?
1) You are assuming behavior that isn't documented. I can imagine that
the first block could occupy, say 16 blocks and depending on the size of
the hole, there could be no fragmentation.
And it is.
3) What no one seems to be mentioning is that we are trying to emulate
UNIX behavior here. If the above is an issue for Windows then it could
also be an issue for UNIX.
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