Date: Wed, 15 Apr 1998 10:50:04 -0700 From: "Eric A. Davis" <edavis@nas.nasa.gov> To: edavis@shark.nas.nasa.gov Cc: sfarrell+lists@farrell.org, Dan Nelson <dnelson@emsphone.com>, "Matthew N. Dodd" <winter@jurai.net>, Eivind Eklund <eivind@yes.no>, freebsd-hackers@FreeBSD.ORG Subject: Re: how to add new system calls... Message-ID: <199804151750.KAA26187@shark.nas.nasa.gov> In-Reply-To: edavis's message of Wed, 15 Apr 1998 10:40:33 -0700.<199804151740.KAA26082@shark.nas.nasa.gov>
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On Wed, 15 Apr 1998 10:40:33 -0700 "Eric A. Davis" wrote
>
>On 15 Apr 1998 12:07:36 -0500 sfarrell+lists@farrell.org wrote
>>Dan Nelson <dnelson@emsphone.com> writes:
>>
>>> In the last episode (Apr 15), Matthew N. Dodd said:
>>> > On Wed, 15 Apr 1998, Eivind Eklund wrote:
>>> > > YES! I've been missing this since I left my Amiga 5 years ago!
>>> > >
>>> > > Does the above imply watching for changes in directories, too? Ie,
>>> > > file added to directory, notification sent...
>>> > >
>>> > > What level of notification? Do you get information saying 'file so
>>> > > changed atime to XXX'/'file XXX added to directory', or just a flag
>>> > > saying 'event so happened on descriptor so'?
>>> >
>>> > Mmm... tripwired
>>>
>>> Sort of like tripwire, but in real time. The Amiga has a feature where
>>> you could monitor a file or directory for changes. Imagine cron
>>> getting a signal when /var/cron/tabs changes. Or any other daemon that
>>> has a config file. There's a description of the function (but not the
>>> assosicated structures unfortunately) at
>>
>>Also applicable, perhaps, to GUI items like file managers so they do
>>not need to poll the directory.
>>
>
>
>Let me tell you what we are doing here at the NAS. We have approx 200 users
>publishing web pages. All web pages are located on a central 'build' box
>were the users do their editing. This 'build' box is a powerful SGI system
>running IRIX 6.2. The IRIX kernel has a facility called imon & fam that
>allows real time monitoring of the filesystem.
>
>I wrote an application that monitors _all_ the web files. There are over
>xxxx files and directories that are being monitored. This has worked out
>_extremely_ well for us. Any time a change occurs within these filesystems
>my application immediately notices it and copies/updates/makes the changes
>on our actual server located in a DMZ. This is great because using this
>paradigm we can also manage the ownership and permissions of the files on
>our servers.
>
Oops, just to clarify the above. I forgot to put in the actual number of
files/dirs being monitored.
We have just under a million file/dirs being monitored by the kernel and are
receiving about 20,000 events a day. And it works beautifully.
- e
--
Eric Allen Davis Network Engineer
edavis@nas.nasa.gov NASA Ames Research Center
Voice: (415)604-2543 NAS Systems Division
Pager: (415)428-6931 http://www.nas.nasa.gov/~edavis
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