Re: [BAD] the whole server down with a red-alert-like attack
On Sat, 26 Jan 2002 00:17, Peter Billson wrote:
> > IMHO something that runs every minute should not be in cron, even
> > something that runs every 5 minutes possibly shouldn't be in cron.
>
> Could you tell me why that is so? I often run things from cron that
> run every 5 mins and have never run into a problem... but then again I
> often do stupid things repeatedly! :-)
If it takes more than 5 minutes to run then things get bad. Also if there is
some transient condition that blocks the script then the results can be
catastrophic.
I once had a cron job run every 5 minutes that ran "df" and logged the output
(sounds really safe doesn't it).
But then the NFS server crashed overnight and all the df processes blocked,
by the next morning there were enough df instances blocked that when the NFS
server resumed operation the NFS client thrashed itself to death and had to
be rebooted.
--
http://www.coker.com.au/bonnie++/ Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/ Postal SMTP/POP benchmark
http://www.coker.com.au/projects.html Projects I am working on
http://www.coker.com.au/~russell/ My home page
Reply to: