What is mod_rewrite? Mod_rewrite is a rule-based rewriting engine (based on a regular-expression parser) to rewrite requested URLs on the fly. It supports an unlimited number of rules and an unlimited number of attached rule conditions for each rule, to provide a really flexible and powerful URL manipulation mechanism. The URL manipulations can depend on […]
Pesky Udev Rules Have you ever replaced a network interface (NIC) or performed a chassis swap? If you are an administrator or IT professional the chances are good that at some point or another you have had to perform one of these. Wait! "What's this!?" You say to yourself as you think your just about to […]
Postfix Postfix is a free and open-source mail transfer agent (MTA) that routes and delivers electronic mail. It is intended as a fast, easier-to-administer, and secure alternative to the widely-used Sendmail MTA. Postfix is released under the IBM Public License 1.0 which is a free software licence. It was originally written in 1997 by Wietse Venema at the IBM Thomas […]
postfix - Postfix Control Program. Switch Description check Warn about bad directory/file ownership or permissions, and create missing directories. start Start the Postfix mail system. This also runs the configuration check described above. stop Stop the Postfix mail system in an orderly fashion. abort Stop the Postfix mail system abruptly, Running processes are stopped immediately. […]
Hypervisor Classifications Hypervisors, in general, are historically classified in two types: Type 1 hypervisor (Bare-Metal Architecture) – This is a hypervisor that runs directly on a given hardware platform. A Guest OS then runs at the second level above the hardware. This model represents the classic implementation of virtual machine architectures. The original hypervisors, SIMMON […]
What is Xen? Xen is an open-source type-1 or baremetal hypervisor, which makes it possible to run many instances of an operating system or entirely different operating systems in parallel on a single machine (or host). Xen is used as the basis for a number of different commercial and open source applications, such as: server […]
So what is really going on? Linux is borrowing unused memory for disk caching. This makes it looks like you are low on memory. The disk cache also known a dcache is an important part of your system that is generally split into two separate components, Buffers and Cache. Each of these portions of the […]
Whether you are an engineer or an end user, most of us who work on critical systems find ourselves concerned with the availability of services those systems provide every day. There are times when these systems fail for one reason or another and we find ourselves interested in just how long those systems may have […]
Centering Gaining Control at the Start of a Performance Centering helps you stay calm and grounded. © iStockphoto/spooh It's the worst nightmare for many people: You're about to give a speech before hundreds of people, and the speech could impact your career for years to come. Performance experts and life coaches have told you, time […]
The Inverted-U Model Balancing Pressure and Performance (Also known as Yerkes-Dodson Law) Get the pressure right. © iStockphoto/SteveStone Have you ever worked on a project that had a tight-but-achievable deadline, and that needed your unique, expert knowledge for it to be completed successfully? Even though you found it challenging, you may have delivered some of […]
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