On Mon, 20 Aug 2001 at 10:15, Raymund dos Remedios wrote:
> You might want to try directing std-out of the cron output to
> /dev/null. On the Vixie cron, the std-err will still get mailed to
> the crontab owner unless you override the MAILTO.
While true this is only necessary when running programs that will spit out
known messages regularly. sync shouldn't send anything to stderr, and if
it does, you'd sure like to know, right?
>
>http://www.linuxdoc.org/LDP/solrhe/Securing-Optimizing-Linux-RH-Edition-v1.3/gen-optim.html
> ... talks about bdflush and buffermem.
I looked at the documentation, and just thought I'd let the list know that
the optimizations recommended are meant to "speed things up" by doing such
things as allowing 100% of the buffer to be dirty before flushing them
onto disk.
This has absolutely nothing to do with making bdflush act as a "poor man's
UPS", and in fact increase the chances of data loss as data fills your
buffer. Imagine if 99% of your buffer is full and the power dies out on
you.
My initial message about bdflush was meant to do something similar to
running sync every second, by telling bdflush to flush ordinary data
buffers onto disk at a maximum of 100 jiffies (1 second). IMHO this seems
to be a "cleaner" implementation, compared to running sync every second.
If I am wrong, someone please help enlighten me. I've sent this "bdflush
vs sync" recommendation to the XFS list and haven't gotten any "sync is
better" responses.
I also wonder why RedHat needs the _network_ to be restarted for bdflush
optimizations to take place. Aside from the fact that I don't see what
bdflush has to do with the network, this sure sounds Micro$ofty.
On my system (running Debian GNU/Linux) I have a script bdflush in
/etc/rc.boot. This gets run at boot time, and is where I put my customized
boot scripts. To run my scripts without rebooting, I just
"/etc/rc.boot/bdflush". This, in turn, uses the sysctl file
/proc/sys/vm/bdflush to reconfigure the bdflush daemon on the fly, which
is how things should be done anyway. :)
> * * * * * root /bin/sync
> ^^^^
Makes sure /bin/sync is run by the root user. :)
--> Jijo
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