Prentice Bisbal wrote:
The more services you run on your cluster node (gmond, sendmail, etc.)
the less performance is available for number crunching, but at the same
time, administration difficulty increases. For example, if you turn off
postfix/sendmail, you'll no longer get automated e-mails from your
system to alert you to a problem.
My question is this: how extreme do you go in disabling non-essential
services on your cluster nodes? Do you turn off *everything* that's not
absolutely necessary, do you leave somethings running to make
administration easier?
I'm curious to see how everyone else has their cluster(s) configured.
Thanks for all the interesting responses. Very informative and helpful.
I'm surprised no one mentioned unnecessary cluster configuration. The
stock kernels from the distros have support for just about every feature
and piece of hardware enabled. I understand the modular nature of the
kernel, but I'm sure for every kernel module that's added, some
addtional work must be added to the core kernel to load that module and
communicate with it, or check for when it needs to be loaded.
I'm looking the output of lsmod on one of my new cluster nodes (running
ROCKS - I haven't configured it yet), and I the following modules listed
in the output, that I don't think have any purpose on a cluster node
(please correct me if I'm wrong):
parport_pc
lp
parport
pcspkr
battery (for laptops?)
backlight (for laptops?)
+ plus a lot of iptables related modules
There are more that are questionable, but they may in fact be necessary
- I'm not an encyclopedia on kernel modules. Is anyone else surprised
that IP tables is configured on a cluster node. Everytime an IP packet
comes in, the kernel must now stop to check it and make sure it meets
the criteria to be accepted. That's GOT to take some CPU time.
I wonder how many cluster nodes out there are running LVM, since RHEL
always insists on setting it up.
--
Prentice
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