Steroids for Rsync!

Scott Becker scottb at
Thu Mar 3 00:11:52 GMT 2005

I've been researching the state of 'file alteration monitoring' 
technology on Linux. Famd uses dnotify to inefficently monitor a handful 
of directories. The replacement for dnotify is being worked on in the 
kenel and it's called inotify. If I understand it correctly and they get 
it finished, it would be an awesome addition to rsync. With it, you 
could run rsync to update a remote system (push mode) and keep it 
up2date. With inotify efficiently feeding 'file opened for write was 
just closed' notifications to rsync, it could efficiently and 
continuously mirror an active file system. With enough bandwidth, the 
time lag could be mere seconds.

My challenge is to mirror 300 gigs of half meg files on to three remote 
filesystems, afap. Most of the files are 'write and leave for two 
months' with some being 'write 4 times a day' so rsync should be perfect 
if it can be told right after the file is created. We are installing 
fiber to our building so this might be the perfect combination to come 
up with a five second mirror performance.

Can rsync be set up with: here's the src dir, here's the remote dir, now 
here's a relative list of files I want you to sync? Perhaps being fed 
one at a time via a pipe. The pipe thing wouldn't be needed if rsync 
used inotify directly.

Right now I'm using a homebrew, ftp utility over a T1 with hours of 
back-log. I'm excited about the prospects.


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