File Locking

[lists at trcintl.com]

On Mon 18 Aug 2008, [EMAIL PROTECTED] wrote:
> 
> >> The way I solved this problem for a data-mirroring system was to use a
> >> small wrapper script that ensures only one invocation of rsync is ever
> >> running at one time. This proved to be a robust solution for our situation.
> 
> >> --Kyle
> 
> Thanks for the idea but I sometimes need more than one copy to run at the 
> same time so that won't work.  File locking is about the only option I can 
> see.

>> If you need to run more than one rsync over the same tree at the same
>> time, you may need to rethink your tree layout and/or your approach to
>> whatever problem you're trying to fix.  Running two rsyncs sequentially
>> will usually be faster than two concurrent ones, as that might cause
>> disk thrashing (the heads are continually seeking to and from where the
>> respective rsync processes are working).

>>  Paul Slootman

Thanks again, but that is still not what I am looking for.  Perhaps more info is needed.  

I have an identical set of directories at two locations.  When a file is added to one location, I'll call it the source side, I want to run a script that picks up that file and copies it to the other location, say the destination side.  Simple enough. 

However, I want to schedule the script to run, say every 15 minutes.  That way if a file is put on the source side, the cript will pick it up and begin copying it.  However, if the file is a few hundred MB, it might take longer than 15 minutes to copy it.  So the next time the script runs, I need rsync to skip that file since it is still being copied from the first run and move to the next file.  That same thing might be repeated during the next run.  

In other words, I can't wait until the first run has completed the large copy to begin copying additional files.  I want to start a second, third, fourth, etc copy that begins working on any additional files that may have been placed on the source side.


Thank you all again for the input, but it still looks to me like I need some type of file locking.  Again, all other input is welcome because there might be a better way.

- Kyle