Date: Sun, 29 Oct 2000 23:26:54 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: David Preece <davep@afterswish.com> Cc: freebsd-hackers@freebsd.org Subject: Re: Filesystem holes Message-ID: <200010300726.e9U7Qsc73333@earth.backplane.com> References: <Pine.BSF.4.21.0010291907320.27883-100000@ren.sasknow.com> <5.0.0.25.1.20001030172530.00a06070@mail.afterswish.com>
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:
:Presumably writing into these holes repeatedly is a none-too-efficient
:affair (requiring moving all the stuff on either side), or am I missing the
:point slightly?
:
:Dave :)
It isn't quite that bad, but it isn't a walk in the park either.
Since data blocks are referenced from a block table, inserting new
blocks is cheap. However, this means that data may not be physically
ordered in the file -- if your read crosses a block boundry it may require
an extra seek. FreeBSD's FFS does have the reallocblks feature turned
on and this will cause the filesystem to try to reorder nearby blocks,
but it was never designed to handle sparse files so....
-Matt
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