The document discusses optimizing WordPress performance through virtual private server (VPS) hosting compared to shared hosting. It highlights limitations of shared hosting, the potential benefits of a VPS with configurations like PHP opcode caching and MySQL query caching, and provides best practices for security and performance enhancements. It concludes with recommendations for VPS providers and additional tips for setup and maintenance.

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Make WordPress Fly with Virtual Server Hosting
Vladimir Lasky
http://wpexpert.com.au/
WordCamp Sydney 2014

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Is This For Me?
Sick of waiting for WP admin pages and edit screens to load in your browser?
Tired of wrangling with page caches, object caches and minifying plugins?
Running a database-intensive WordPress site, e.g. e- commerce site?
Prepared to roll up your sleeves to get a better experience?
Brave enough to forego the “walled garden” of a cPanel in exchange for true freedom and flexibility?
Then YES!

3. Shared Web Hosting
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How Shared Web Hosting Limits You
Throttling of Resources
–Network bandwidth
–Running Processes
–Disk I/O
Limited ability to tune & reconfigure services
No PHP Opcode caching
Might have MySQL query caching enabled, but likely overcommitted

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Why Caching Plugins Are Not The Answer - 1
Two main categories of caching plugins:
–Page caching (e.g. WP Super Cache, Hyper Cache)
–Object Caching
These have cache invalidation overhead/delays
–When the underlying data changes, caches must be explicitly purged or one must wait for expiry.
–Purging, rebuilding caches causes performance hit – especially if the cached data is stored on disk
–Stale caches cause non-current information to be displayed
–Frequently cause issues with plugins/dynamic pages

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Why Caching Plugins Are Not The Answer - 2
They provide no help in speeding up the backend (WordPress Admin) and usually do nothing for users who are logged in.

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What About Cloudflare?
A very popular Reverse-Proxy/CDN service
Some useful features, but you are dependent on them
Have a “free” plan, but no guarantee it will stay free
CDN based on object pull, so can have cache invalidation issues
Doesn’t speed up backend (WordPress Admin)
More comments on CDNs later

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What About Minifying Plugins?
These aggregate your site’s CSS and JS files and compress them by removing white space, new lines comments and block delimiters.
Examples:
–Better WordPress Minify
–Autoptimize
Somewhat reduce the total requests required to load your site and the amount of data transferred
Good in theory, but in practice often break things and require much tweaking to work right

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Why Host WordPress on a VPS?
You can use PHP Opcode Caches, MySQL Query Caches and other performance enhancers that don’t have these issues
You have the full ability to customise and tune services for performance

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What is a VPS?
A Virtual Private Server (VPS) is your very own virtual machine (VM) running in a datacentre.
The physical server or Virtual Server Host, will be running multiple VMs simultaneously – yours and other clients of your hosting provider, but only yours is visible to you.
Cost depends on desired specs – e.g. RAM, disk space, CPUs, monthly data traffic
Start from as little as $5/month, but can be hundreds for something hefty

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How Do You Administer a VPS?
A Linux VPS is generally accessed via SSH
A Windows VPS is generally accessed via RDP
Usually there is a facility to view and control the virtual console, e.g. if the VM hangs and needs to be reset or reimaged.
You can install and run anything you want (subject to provider’s Acceptable Use Policy)

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Common Virtual Private Server Types
OpenVZ
–Based on containerization
–Efficient, but does not allow users to change OS kernel version or have dedicated swap space
–Usually offered at lower price
Xen
–Full ability to customise all aspects of VM configuration
–Allows dedicated swap space
–Some performance overhead
–Usually more expensive

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Why Hosting Control Panels Are Evil
Take over your system – very hard to get rid of or change
Commercial ones cost money, e.g. $150/yr for cPanel
Free ones could be abandoned at any time. Risk of security holes.
Are rather inflexible – you have to wait for updates to support/take advantage of new features in other packages

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The Plan
Host WordPress on a Pure SSD VPS with CentOS 6.5 x64. Dual CPUs and 2GB RAM is nice.
Install a PHP Opcode Cache and allocate 120MB RAM
–Choose Zend Optimizer if using PHP 5.5 w/single WordPress installation
–If Multiple Sites or Older PHP, then XCache
In MySQL config file, enable the Query Cache and allocate 32MB RAM. Make the key buffer/buffer pool
Configure Apache to launch PHP-FPM in FastCGI mode and communicate using Unix Sockets
Configure WordPress to access MySQL using Unix Sockets

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Our Performance-Enhanced Configuration

16. Common Shared Hosting Configuration
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Differences from a Default Installation
PHP operates as a standalone service (PHP- FPM) instead of as an Apache module (mod_php)
Apache communicates with PHP-FPM using Unix Sockets instead of TCP sockets
A PHP Opcode Cache is installed
The MySQL Query cache is enabled
WordPress DB_HOST in wp-config.php is set to ‘localhost’

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Benefits of Our Approach
Not radically different from a default install
Excellent “bang for buck”
No cache invalidation problems
No plugin incompatibilities
Everyone sees the most current state of your site
Logged in users and people working in the backend will enjoy a speed increase

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Why CentOS?
Free Linux distribution 100% compatible with Redhat Enterprise Linux – popular Linux distribution designed for servers
Offered by the vast majority of hosting providers
Security patches are released speedily
Experts are abundant

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Why Unix Sockets?
Less overhead – avoids all network layers below transport
Lessens risk of ephemeral port exhaustion if site is bombarded with requests (it does happen)
More secure – they only accept connections from localhost

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Why Pure SSD VPS Hosting?
HDDs respond to random I/O like busy elevator in office block – big slowdown when lots of random requests
SSDs like elevator that teleports to any floor – cope far better with high, random I/O loads
All server files and databases stored on Solid State Drives
Greatly improves efficiency, performance of Shared and Virtual Server Hosting
Beware of “SSD-cached” storage – not as good

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Who Provides Pure SSD Virtual Server Hosting?
Hosted Abroad:
–Linode
–DigitalOcean
Hosted in Australia:
–Exigent
–Crucial
–ServerMule
–VPSBlocks
More companies are introducing Pure SSD solutions
Australian Pure SSD VPS hosts more expensive and offer lower data limits, but “there’s no place like home”.

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PHP Opcode Caches - I
The only way to truly make WordPress run faster
WordPress is a PHP program
When PHP code is first executed, it is compiled into bytecode and stored in shared memory
Future requests will avoid parsing and disk I/O overhead
120MB is rough yardstick

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PHP Opcode Caches - II
Zend Opcache
–Bundled with PHP 5.5
XCache
–Not as fast as Zend Opcache
+ Recognises identical copies of PHP files
+ Saves lots of RAM if you have multiple WordPress sites

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MySQL Query Cache
WordPress and plugins sends many identical SQL queries to the server each time a page loads
MySQL can be configured to cache the results, avoiding the need to parse and execute the query
The Query Cache is automatically invalidated whenever the database is updated
Transparent to WordPress and plugins
32-64MB is a useful size

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Avoiding CDN Hassles
If you use a CDN for your images, videos or other assets, ensure that it is configured to operate in “Origin Push” mode
This means that WordPress will upload content to the CDN whenever it is added or updated
This avoids cache invalidation issues
W3 Total Cache plugin supports Origin Push CDN integration for several CDNs, e.g. Amazon, MaxCDN

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Anything Else To Speed Things Up?
Enable the Apache module mod_deflate to compress HTML, text, CSS and JavaScript source files before they are sent to the client.
This speeds up site loading and reduces the amount of data transferred.
This will work on your current shared host as well!

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Virtual Server Security Tips - 1
Long 20-character true random passwords (use KeePass to generate and store them)
Regularly apply CentOS software/security updates
–Single command: “yum update -y”
Configure firewall using iptables, to only permit traffic from authorised ports
Install Fail2ban, bfd or similar brute-force attack prevention system
Appropriate WordPress Security measures (refer to previous presentations)

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Virtual Server Security Tips - 2
Be able to “abandon ship” - keep DNS/Email on separate server, so you can relocate if your server is ever compromised (p0wned)
Reminder - only UNIX domain sockets for comms between Apache <-> PHP-FPM and WordPress <-> MySQL
Perform file transfer to/from server using SCP (operates over SSH)
Alternatively, install Pure-FTPD w/SSL to support FTPS

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Too Much Hassle! Is There An Easier Way?
Get someone else to set it up and/or do periodic maintenance
Many Virtual Host providers offer a Virtual Server management service for an extra monthly fee
You can also contact SAGE-AU - Australia’s peak body for System Administration Professionals. They can help you find a local Aussie for casual SysAdmin work:
–https://www.sage-au.org.au/contact-us

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Conclusion
Additional Tips & Configuration Notes:
–http://wpexpert.com.au/wordcamp-sydney-2014
–Will have configuration examples for PHP-FPM, Apache and MySQL
Questions and Comments:
–http://wpexpert.com.au/contact-us/