Presentation slides from Vladimir Lasky's talk "Make WordPress Fly With Virtual Server Hosting", presented on Sunday 28th September at WordCamp Sydney 2014.

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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/