Re: [gentoo-user] kernel notification of file system changes

[Florian Philipp <lists@f_philipp.fastmail.net>]

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Am 05.05.2010 15:34, schrieb Stroller:
> 
> On 5 May 2010, at 07:54, Iain Buchanan wrote:
>> ...
>> I'm looking for some kernel-based notification of changes to my file
>> system.  I've been looking at inotify, but it's not exactly what I want.
>>
>> Basically I want to know if _any_ write occurs anywhere.  I don't want
>> to register a whole bunch of files to watch, I just want to watch an
>> entire mount.
> 
> man inotify(7):
> ... When a directory is monitored, inotify will return events for the
> directory itself, and for files inside the directory.
> 
> 
> Am I missing something?
> 
> 
> This article was posted to a different froup recently:
> http://www.ibm.com/developerworks/linux/library/l-inotify/index.html
> It looks interesting.
> 
> 
> Stroller.
> 

To repeat my comment on Iain's original "backup to a cold-swap drive"
thread, Inotify has two drawbacks which make it hard or even impossible
to use for Iain's use case:

a) It does not work recursively which means that you have to create a
new handle for each subdirectory. Of course, this only means more work
for the programmer but there is also the problem that

b) As far as I know, Inotify does not scale very good, at least not good
enough to monitor a whole system. /proc/sys/fs/inotify/max_user_watches
is 65535 on my system.

On the other hand, I've never tried to increase that limit and just let
it run on a deep directory structure. Who knows, maybe it actually works.

Hope this helps,
Florian Philipp


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