Sorry to be off topic, but I'm looking to start monitoring my box too, what are you using to generate these graphs, and does it use a web interface?

Thanks!

Those look like the "plain ol'" Linode graphs, generated using RRDTool based on telemetry from Linode's SCADA [1]. RRDTool is probably the de facto standard in the *nix world for collecting, managing, and graphing time series data sampled on regular intervals using a round-robin database. Munin and Cacti are two great systems that use RRDTool under the hood.



There's also the Graphite system, which uses its own round-robin database system, Whisper. This is an entirely different bowl of cherries, built for scale and speed, and serves as the foundation of some religions, e.g. Etsy's Church of Graphs.



... but if you just want the graphs from the original poster, log into the Linode Manager and click on your Linode, then scroll down.

[1] I think SCADA is an appropriate term to describe "the things between {api,manager}.linode.com and the hypervisor". Just because it controls the flow of clouds instead of molasses doesn't mean it's not industrial.

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lol I realized after I posted that it was the same graph from the linode manager.

I'm thinking about using awstats, wow I haven't heard of any of those. Thanks for the suggestions

Guspaz - great insight as always.

I was thinking smush.it as well - just worried about load on the server as I SMUSH them.

mod_deflate might make some sense as well. I'll give it a go with your suggestions of Max Clients.

I'm assuming if I max it all out I could hit a threshold of clients not loading the site at all because all of Apache is busy. No way to track that I'm assuming since they won't actually hit the apache server?

to that last point, at this off peak hour, my report from apache:


72 requests currently being processed, 4 idle workers

thinking past apache, I could jump on the LEMP bandwagon...

Thoughts on mod_cache and MPM Prefork?

If you are using WP, check w3 total cache + APC, it's a solution i'm using and it gives some benefit.

I use it on LEMP

Yea I Was going to check out W3 when I put Cloudflare in front. Apparently they work together which is good.

I run a cron job once a day to search the Apache error log for MaxClients.

sudo grep MaxClients /var/log/apache2/error.log

I hardly ever get anything, but occasionally I get 1 or 2 entries. So, not a big deal. If it were a lot entries though, I'd be worried.

I believe you had earlier enabled keepalives, you're going to want to disable those, since they consume slots that don't otherwise need to be in use. Beyond that, you do have some room to play with, so you can increase your maxclients to where you feel comfortable. Take a look at how much RAM your larger apache processes are taking up, and increase it (leaving a good chunk of RAM free for disk caching in your calculations). For example, if your larger Apache processes are 80MB each, then on a 4096, maybe a maxclients of 40 would be acceptable.

One thing you can also consider doing is switching apache from mpm_prefork to mpm_worker, which is a lot more efficient, but more difficult to set up. It requires setting up PHP as a fastcgi (usually using FPM, I believe) since PHP doesn't like multithreading, and there are some other considerations to take into account, but it saves a ton of RAM because you pick the number of PHP processes, and you don't need a copy of PHP loaded into RAM just to handle a static request.

For much help in tweaking Apache beyond this, you'd really have to turn to the Apache wizards around here. I'm a lighttpd user, and many people around here use nginx, both of which are single-process single-threaded servers; you don't have to manage any of this stuff to the same extent because they're much simpler, but I'm a bit biased because I've been using lighttpd for a *very* long time.

In terms of load concerns regarding smush.it, I'm not sure I follow; it's not an active service that you integrate, it's just an image processing tool. You upload your images, it optimizes them, you download the result. Smaller images won't really help your server load, just your bandwidth bill, and probably not dramatically (but every bit helps, right? A bit from smush.it here, a bit from mod_deflate there, a bit from javascript minifiers there, it all adds up)

awesome, thanks for this.

as for smush.it I meant the server load as it optimizes the images (cpu crunching images etc) but maybe if I'm reading correctly, Yahoo's servers do this.

I'm switching to Cloudflare + Wc3 cache tomorrow morning to see how it handles.

I'm also considering nginx as an alternative

Also to the MaxClients note - I don't think 40 would work because of the amount of traffic the site gets.

Currently, at an off peak time, the http count is:

root@li [~]# pidof httpd | wc -w
74

I'm at MaxClients = 100 right now.

I do have keep alive off as well.

Just remember to use mod_fastcgi, not mod_fcgid. FPM is not necessary at all, tho it'd probably help. I'll tell you in a year or so after the next Debian upgrade, 6.0.x doesn't have FPM.

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rsk, providing useless advice on the Internet since 2005.