I’m a terrible artist but, if you have an idea for a technical drawing please send me a DM on Twitter (@ChrisShort) or e-mail. Thanks!

OSI Model

The Open Systems Interconnection model (OSI model) defines a concept where every function of a computing system resides at one of its seven levels. When people say, “Layer 3 routing” or “L7 load balancing” they are referring to the OSI Model. It is an incredibly handy tool for troubleshooting as it reminds you to check the system at each layer. The official documentation on the OSI Model can be found on the ISO site (yes, that’s confusing). [Read More]

PHP Memory Directives Relationship

I recently had to templatize PHP configurations using Ansible and Jinja2. I had to do some research to ensure that the memory directives that were being defined were actually valid. The three directives I was tinkering with were: memory_limit upload_max_filesize post_max_size These three directives values’ are actually tied together. memory_limit is the max amount of memory that a script can consume. upload_max_filesize defines the largest size a file upload can be. [Read More]