Today, on my 28th birthday, I'm finally delivering on a promise to my readers which I made about two months ago. I've on how to host a web application redundantly in a cloud environment. While it's still a bit of a rough draft, it should be a good starting point for those who haven't worked in virtualized environments before. Also, it may show some of the more experienced systems administrators a new way to do things.
The guide:
As always, if you find anything in the guide that needs improvement, I'm all ears.
If you're running an operation on a large number of rows within a table that uses the InnoDB storage engine, you might see this error:
ERROR 1206 (HY000): The total number of locks exceeds the lock table size
MySQL is trying to tell you that it doesn't have enough room to store all of the row locks that it would need to execute your query. The only way to fix it for sure is to adjust innodb_buffer_pool_size and restart MySQL. By default, this is set to only 8MB, which is too small for anyone who is using InnoDB to do anything.
If you need a temporary workaround, reduce the amount of rows you're manipulating in one query. For example, if you need to delete a million rows from a table, try to delete the records in chunks of 50,000 or 100,000 rows. If you're inserting many rows, try to insert portions of the data at a single time.
It's no secret that I'm a big fan of as a blog and CMS platform. While it does have its problems, it's relatively simple to set up, it's extensible, and — when properly configured — it has great performance. The plugin has been a staple on my WordPress blogs for quite some time and it has solved almost all of my performance problems.
However, when you load up quite a few plugins or a heavy theme, the performance will dip due to the increased number of stylesheets, javascript files, and images. You can compress and combine the stylesheets and javascript to decrease load times, but this may not get the performance to a level you like.
I was in this situation and I found a great solution: the plugin and the service.
To get started, and set up an account. Their current promotion gives you 1TB of CDN bandwidth for one year for $10 (regularly $99). Once you sign up, do the following:
Click Manage Zones
Click Create pull zone
At this point, you'll see a list of form fields to complete:
Enter an alias for the pull zone name
The origin server URL is the URL that's normally used to access your site (i.e. rackerhacker.com)
The custom CDN domain is the URL you want to use for your CDN (i.e. cdn.rackerhacker.com)
The label can be anything you'd like to use to remember which zone is which
Enabling compression is generally a good idea
Once you save the zone, MaxCDN will give you a new domain name. You'll want to create a CNAME record that points from your CDN URL (for me, that's cdn.rackerhacker.com) to the really long URL that MaxCDN provides.
STOP HERE: Ensure that all of your DNS servers are replying with the CNAME record before you continue with the W3 Total Cache installation and CDN setup. If you proceed without waiting for that, some of your blog's visitors will get errors when they try to load content via your CDN domain.
You're ready for W3 Total Cache now. Install the plugin within your WordPress installation and activate it. Hop into the settings for the plugin and make these adjustments:
Enable Page Caching and set it to Disk (enhanced)
Enable Minify and set it to Disk
Enable Database Caching and set it to Disk
Leave the CDN disabled for now, but flip the CDN Type to Origin Pull (Mirror)
Press Save changes
Click CDN Settings at the top of the page and configure the CDN:
Enter your CDN domain (for me, it's cdn.rackerhacker.com) in the top form field
Leave the other options as they are by default and click Save changes
W3 Total Cache should prompt you to clear out your page cache, and that would be recommended at this step. If you fully reload your blog's main page in your browser (may require you to hold SHIFT while you click reload/refresh) and check the page source, you should see your CDN URL appear for some of the javascript or CSS files.
You may discover that some CSS files, stylesheets, or images aren't being loaded via the CDN automatically. Luckily, that's an easy fix. Under the Minify Settings section of the W3 Total Cache plugin settings, scroll to the very bottom. Add in your javascript or CSS files via the form fields at the bottom and the plugin should handle the minifying (is that even a word?) and the CDN URL rewriting for you.
