On Aug 8, 2006, at 12:34 AM, Darren J Moffat wrote:
Adam Leventhal wrote:
Needless to say, this was a pretty interesting piece of the
keynote from a
technical point of view that had quite a few of us scratching our
heads.
After talking to some Apple engineers, it seems like what they're
doing is
more or less this:
When a file is modified, the kernel fires off an event which a
user-land
daemon listens for. Every so often, the user-land daemon does
something
like a snapshot of the affected portions of the filesystem with
hard links
(including hard links to directories -- I'm not making this up). That
might be a bit off, but it's the impression I was left with.
Which sounds very similar to how NTFS does single instance storage
and some other things.
The interesting thing here is that this means HFS+ and NTFS both
have a file event monitoring framework that is exposed up into
userland. This is something that would be VERY useful for
OpenSolaris, particularly if we could do it at the VFS layer.
Anyhow, very slick UI, sort of dubious back end, interesting
possibility
for integration with ZFS.
:-) Which is the opposite of what "we" tend to do, slick backend
and no
GUI and an integration challenge on the CLI :-)
Both FreeBSD[1] and Apple[2] (of course) use the kqueue for file event
notifications. openSolaris's FEM [3] "starter-kit" would be an
interesting
place to visit and build upon..
-- Robert.
[1]: http://people.freebsd.org/~jlemon/papers/kqueue.pdf
[2]: http://developer.apple.com/documentation/Darwin/Reference/
ManPages/man2/kqueue.2.html
[3]: http://cvs.opensolaris.org/source/xref/on/usr/src/uts/common/sys/
fem.h
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