Posted on: January 5th, 2011 by Famous Phil

For any CPanel administrator, migrating accounts between servers is an issue that comes up now and again and I have not found any really great sources online on how to do this properly and minimize downtime so I thought I’d write my own guide.  As always, the information provided is on an as-is basis with no warranty that this will work for your situation.

Background:
Since November, the Matthouse CPanel server (int) was sick.  It started in early November by going offline with no response (my nagios monitor caught it).  I thought nothing of it and hard-rebooted the machine.  I read the error logs and found nothing out of place. 

Aside: The kernel is the lowest level of an operating system, it is what makes disk access and other critical functions available to an operating system, BIOS typically calls a bootloader that then runs the kernel.  Kernel panics are basically a condition when the kernel doesn’t know how to handle an error, and since the kernel holds the operating system up, the computer crashes and a BSOD (or equivalent) is displayed on the screen.

The next night, int crashed again, but because of the non-existent error logs, I decided to wait for a KVM device to be connected so that I could read the console screen.  Thankfully when a system crashes, it leaves information up on the screen that is helpful to the administrator.  In my case, the quota service was causing the panic.  I disabled the quota service after rebooting the system and this helped for about a week.  Then it happened again with a similar error on the console.  After a lot of digging, I ran out of ideas and finally had the server checked for hardware problems.  All the tests passed successfully so I let it be.  Strange enough it made it for another week then the same problem occurred.

At this point, I thought it would be in the best interest of my clients to get them off the existing server and onto some new hardware in hopes of finding a long term solution to this problem.  This is where the title of this blog comes into play.  How do I implement a new CPanel server and move all the customers to it with almost no downtime?  If you wish to know the solution, please open up the full version of this blog and read on.

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Tags: BSOD, CPanel, crash, DNS, Kernel, Kernel panic, migration, Transfer, TTL, WHM
Posted in Hosting / Server Administration
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Posted on: February 18th, 2009 by Famous Phil

As the owner of a hosting company, I have made several decisions regarding which server to use, what kind of control panel should I provide, should I add features to my hosting, how many resources should I include, etc.  In my opinion, one of the most important decisions in hosting is choosing how your users will use the service, meaning what control panel should I use?  There are many options for Linux including, Plesk, LXAdmin, and the most popular: CPanel.

CPanel is the control panel that I choose to use for Matthouse hosting accounts, but why did I choose CPanel, what are its advantages and disadvantages?

I suppose I should first begin with a small description of what CPanel is.  CPanel allows the hosting client to modify all aspects of their site from an easy to use web-based interface such as FTP accounts, Email accounts, statistics, subdomains, additional domains to host, etc.  CPanel makes it very easy for the hosting company to give the client total control of their website without the requirement of providing full server access.

Here are the advantages of using CPanel:

1. Its very easy to install, just install Linux and run the installation script, it will configure most of your server automatically
2. Cpanel provides a very easy visual interface where you can manage your server.  There are several panels that are meant for administrators, clients, and even email users.  There are also very easy to follow tutorials posted on CPanel’s website for those users who may not know where to start
3. Cpanel automates most of the hosting experience which reduces stress on the hosting company

So, what are the disadvantages of hosting with CPanel?

1. I personally believe that CPanel is meant for websites that are small to medium. CPanel itself is a resource hog and requires at least 256MB of ram on the server to run, and this amount probably won’t even run a website getting 200 hits a day without running out of memory or running into swap space on the server.    Most servers will have much more RAM than this, but a base install should not require more than 50 to 60MB of ram.
2. On a default install, CPanel usually is optimized for a dedicated server with 4 to 16GB of RAM.  Even the VPS Optimized version of CPanel requires additional configuration to keep CPanel within check.  If you don’t do initial configuration in Apache, etc, you may run into memory errors easily since Apache will start up 20 to 30 processes at 1 to 6MB a piece.  In addition, most of the Apache configuration is default and many modules are missing such as Source Gaurdian which will protect PHP code from hurting your server.  In addition, CPanel doesn’t secure SSH or FTP, you you should still install a firewall and tighten SSH security.
3. CPanel is software which contains vulnerabilities just like any other software.    Cpanel updates run nightly, however what happens if someone discovers a security risk and decides to attack your server before the updates are pushed to your server covering the vulnerability?  To come back to my past disadvantage of Cpanel is meant for small to medium sites, I believe this aids to the arguement that big sites are more likely to be hacked than smaller sites.
4. CPanel costs money to license. This is rarely a factor to most big sites and companies because they have that kind of money to spend for something easy to use, however CPanel licenses are not cheap.  This really could be neither and advantage of disadvantage, but its worth sticking on my list of points to consider.

So when would I recommend a CPanel installation?  Thats simple, I’d recommend it for hosting companies that host many sites on a single server.  It reduces stress on the hosting company, and generally these servers have plentiful resources to handle CPanel in its entirety.  Also sites that are generally on shared CPanel hosting are not big enough to have a good probability of being hacked.

When would I not recommend installing CPanel.  I would personally say never install CPanel on a large site that gets over 5000 unique hits a day or more.  CPanel may make administering the site easier, however most sites that are this big bring in a lot of revenue  and paying for CPanel could be just slightly cheaper than hiring an experienced server administrator or a friend to run the server without CPanel.  Installing the core components and configuring them manually will also ensure that you have minimal code that can be hacked (Yes, web servers are software).  I’ve always been taught that the less code you use, the less likely there will be problems with it.

Thats all the time I have.  I might follow up on this depending on how many comments I receive.

Tags: CPanel, Host, hosting, Linux, Manager, Web, WHM
Posted in Hosting / Server Administration
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