Re: Building off Medusa

[David C Sterratt <david c sterratt ed ac uk>]

>>>>> Seth Nickell writes:

 >> The incremental live indexing isn't difficult.  Medusa could use
 >> libfam to gather modifications to files, and reindex them.  I got
 >> it pretty sorted out, although perhaps a "medusa-modifyd" is
 >> needed, which puts filesystem change manifests in a FIFO queue,
 >> and medusa reads the queue and reindexes the filesystem.  This
 >> also helps for offline searches.  The multiuser thing is crucial
 >> to a business setting.  The metadata indexing is crucial for me
 >> (damnit i want to find my MP3).

 > Just so you know... Incremental indexing won't be possible using
 > libfam.  FAM will not scale to monitoring over about 500 files, so
 > you definitely will not be able to get change notification on all
 > the files on a disk.  I would love a way to register with the
 > kernel to be notified whenever *any* file changes, but I don't
 > believe there is such a mechanism.

Apparrently there is a mechanism available in 2.4.19 kernels and
higher that can monitor changes in unlimited numbers of directories.
There is a command line interface to it called dnotify
(http://www.student.lu.se/~nbi98oli/dnotify.html).  I haven't tried it
myself, but it looks as though it should be able to monitor a
directory recursively and tell you when there are any changes to that
directory, though it can't tell you the name of the file that was
changed.

Another project (that supplies its own kernel module and may overcome
the file name limitation of dnotify) is changedfiles
(http://www.bangstate.com/changedfiles/).  Again, I haven't tried this
out.

David.