eBox, Ubuntu, and 256K RAM

[Sam Graf]

This isn't a support question so much as a for-my-information question. I've got a Dell eBox I've mention before, an old OptiPlex GX110 that was part of my first eBox testing. I'm using it as a router and proxy in a test environment. File sharing is enabled but it's not being used to serve files. So basically it's handling an Internet connection on a routine basis.

Over the last few weeks it has begun to become unstable over time and requires periodic restarting. I'm measuring stability here by comparing CPU and load levels over time. When the machine is what I'm calling stable, it spends most of its time idling. CPU loads are regularly under 1% and system load is regurlarly 0.00 to 0.08. At some point this all changes and the CPU runs constantly at a load of 70% to 80% and system loads are constantly 1+. There are no significant changes in the number of running process that I can see, and there are no zombies on a regular basis.

That said, DansGuardian is busier than normal. It's always near the top of the process list, sometimes as multiple instances, even when top is about the only thing the machine is really doing. It's always consuming resources of varying amounts on both the CPU and memory sides. So I suspect that something happens to DansGuardian over time. I suspect that and update somewhere along the line introduced the problem since this is something relatively new for this particular machine. Since the machine is running minimal RAM, I'm wondering if something happens during a swap to break normal operation. This has never happened on the old Asus I've mentioned before, which is running 512 RAM (but of course there are other differences).

So my question is, is it likely that 256 RAM simply isn't enough RAM for router/proxt type applications? Is it possible that over-dependence on swap can break an Ubuntu server? I'd like a better understanding of this before I attempt deploying old hardware with a similar configuration in a high priority production environment.

Thanks for reading.

[javi]

Hi,

So I suspect that something happens to DansGuardian over time. I suspect that and update somewhere along the line introduced the problem since this is something relatively new for this particular machine.

The Ubuntu guys uploaded a new Dansguardian version a couple of weeks ago. From 2.8.8 to 2.9.8, so as you said, this new version could be using more RAM and causing troubles that you didn't have before. As far as I know Dansguardian start quite a few processes.

So my question is, is it likely that 256 RAM simply isn't enough RAM for router/proxt type applications? Is it possible that over-dependence on swap can break an Ubuntu server? I'd like a better understanding of this before I attempt deploying old hardware with a similar configuration in a high priority production environment.

Performance drops dramatically when the system has to swap in/out very often, so yeah, you could be running into that situation. Having said that, if you are only using routing + proxy/content filter, I think we should be able to run those process in 256 MB.

First of all,

Did you only install the eBox modules you needed or instead you used our cd installer which installs by default all the modules and its dependencies? If you did the latter, you should get rid of those modules and dependencies that are not used.

Make sure you have installed apache2-mpm-prefork.

You can also stop the normal apache if you are not using the webserver module:

sudo /etc/init.d/ebox apache stop

eBox 1.2 will use less memory, in order to make eBox 1.0 use less memory you can modify this file:

Code: [Select]

/var/lib/ebox/conf/apache2.conf

Change from:

Code: [Select]

<IfModule mpm_prefork_module>
    StartServers          1
    MinSpareServers       1
    MaxSpareServers       1
    MaxClients            2
    MaxRequestsPerChild   20
</IfModule>

to :

Code: [Select]

<IfModule mpm_prefork_module>
    StartServers          1
    MinSpareServers       1
    MaxSpareServers       1
    MaxClients            1
    MaxRequestsPerChild   200
</IfModule>


[Sam Graf]

Thank you, javi, for the helpful response.

Yes, this was a machine set up from the ISO. So what you're saying is that it might be helpful to go into software management and delete the stuff I'm not using? I did that on another machine during earlier testing but got concerned by the amount of stuff apt-get autoremove wanted to remove after doing deletions in software management. Is it safe to do the delete through the eBox GUI and then let autoremove clean up?

I have an identical OptiPlex not currently in use, so I'm going to set it up according to your suggestions and see what happens. Thanks much!

[Sam Graf]

One other question, for all you network hardware geniuses. Is it possible for a hub (not a switch) to be confused by a proxy? At some point in roughly the same time frame as my Dell started visiting the Twilight Zone I threw a Linksys (Network Everywhere) hub (a piece of loaned out hardware that had been returned) into the test network. Given that hubs are easily confused by physical changes in a network, it dawned on me to ask if they're possibly subject to confusion by any logical processes associated with proxies.