I recently upgraded from Business shared to VPS, and I've had nothing but frustration and headaches since. I really like Lunarpages, and I want to stay here, but I need to have a working site. VPS just ain't doing the job, now or since I transferred.

[Note: I'm an experienced webmaster, but a Linux novice. So I recruited two highly skilled Linux admins to help with the site. I've asked them to join the thread, to add their insight and help iron out the crippling problems we've had with VPS.]

The problem:
Tech support told me that my site was overloading Apache. One of my admins throttled Apache, but it still consumes itself over time. The issue, apparently, is memory usage.

I run a fairly vanilla site, with ~15,000 users a day. I have currently disabled MediaWiki and my Search scripts, to cut down on resource usage until we get things stabilized. The only non-HTML things I have running are a WordPress Blog, phpMyChat Plus, and TFMail form mail.

So why is Apache overloading and consuming all the memory? Why did my site work in a shared environment, but chokes in VPS (where I should have far more server resources)?

Is it a case of too many visitors? I can't imagine that I'm the first guy to run a high-volume site with Lunarpages. Even then, my Alexa ranking is only in the mid-30,000s, so I'm not talking about hundreds of thousands of visitors.

When Apache eventually overwhelms the system, I can't log in through shell. I can't log in to cPanel. I can't even log in to WHM to restart Apache. I can't do anything to fix the problem, and my admins can't stop it from happening in the first place.

Please help!

I'm open to any suggestions.

Nick

Hi NickScipio,

I am sorry to hear about your issues with VPS server. Unfortunately, the stats got cut off and it is difficult to give exact advises. However, from the rest of details you provided your site appears to require more resources than VPS server can provide.

Our shared servers are very powerful machines because they must serve hundreds of shared accounts. While being on shared server your scripts might consume some more resources short amounts of times. If a shared account starts to consume a significant amount of resources continuously for a some reason, we are forced to move it to a temporary server or even suspend if the move is not possible as it starts to affect all customers sharing the same server.

On VPS there are still customers sharing the same server, but the amount of the users is far less than on a shared box. Each VPS is an environment that gives you a virtual UNIX machine restricted by CPU and memory utilization so that it can't cause downtime or performance issues to other VPS accounts. You get administrator's access and can setup any software required. However, it is still not a physical machine and thus can't provide the same performance. It is needed to note that although it is still an upgrade from a shared plan but it can't fit the needs for all the users upgrading.

For example, if an account have 20% for memory usage in cPanel stats, taking in consideration that our shared servers has 4 Gigs of RAM, such account won't get a benefit after upgrade to VPS which is limited by 512 Megs of RAM whereas the site requires around 800 Megs to serve all the visitors.

As per my personal experience, around 15000 users per day visiting blog in WordPress and communicating in a chat causing a high utilization in terms of CPU, Memory and MySQL.  I would really recommend consider a dedicated server for such site.

Regards sites serving hundreds of thousands of visitors, such projects uses dedicated servers and usually more than a single server combining multiple machines in clusters. Architecture of such solutions is beyond scope of this thread.

I hope this makes things clearer.