Get ready for a minute with 61 seconds. Scientists are delaying the start of 2009 by the first 'leap second' a timing tweak meant to make up for changes in the Earth's rotation.
The aged Earth is slowing down in its daily rotation, at least in the current epoch. So a leap second is added (a one-second adjustment added) to our time. This year will be exactly one second longer.
Precise time measurements are needed for high-speed communications systems among other modern technologies such as clusters, GPS, networks. You need to make sure that you are running updated version of ntpd that support leap second for UNIX and Windows computers.
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I've already written about setting the MTU (Maximum Transmission Unit) under Linux including Jumbo frames (FreeBSD specific MTU information is here).
With this quick tip you can increase MTU size to get a better networking performance.
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Virtualization is the latest buzz word. You may wonder computers are getting cheaper every day, why should I care and why should I use virtualization? Virtualization is a broad term that refers to the abstraction of computer resources such as:
- Platform Virtualization
- Resource Virtualization
- Storage Virtualization
- Network Virtualization
- Desktop Virtualization
This article describes why you need virtualization and list commonly used FOSS and proprietary Linux virtualization software.
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Now, mod_fastcgi is configured and running. FastCGI supports connection via UNIX sockets or TCP/IP networking. This is useful to spread load among various backends. For example, php will be severed from 192.168.1.10 and python / ruby on rails will be severed from 192.168.1.11. This is only possible with mod_fastcgi.
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FastCGI is a protocol for interfacing interactive programs with a web server. FastCGI's main aim is to reduce the overhead associated with interfacing the web server and CGI programs, allowing a server to handle more web page requests at once.
Also, PHP is not recommended with multithreaded Apache2 (worker MPM) because of performance and some 3rd party PHP extensions are not not guaranteed thread-safe.
nginx and lighttpd has inbuilt support for FastCGI. For Apache web server you need to use either mod_fastcgi or mod_fcgid.
Why use mod_fastcgi instead of mod_perl / mod_php?
From the wikipedia article:
Instead of creating a new process for every request, FastCGI can use a single persistent process which handles many requests over its lifetime. Processing of multiple requests simultaneously is achieved either by using a single connection with internal multiplexing (ie. multiple requests over a single connection) and/or by using multiple connections. Many such processes can exist, something that can increase stability and scalability. FastCGI also allows programs to get the web server to do certain simple operations, like reading in a file, before the request is handed over. Environment information and page requests are sent from the web server to the process over a TCP connection (for remote processes) or Unix domain sockets (for local processes). Responses are returned from the process to the web server over the same connection. The connection may be closed at the end of a response, but the web server and the process are left standing.
Many web site administrators and programmers are finding that the separation of web applications from the web server in FastCGI (and the simpler SCGI) has many desirable advantages over embedded interpreters (mod_perl, mod_php, etc.). This separation allows server and application processes to be restarted independently -- an important consideration for busy web sites. It also facilitates per-application security policies -- important for ISPs and web hosting companies.
In this quick tutorial, you will learn about Apache 2 + mod_fastcgi + PHP installation and configuration under Red Hat Enterprise Linux / CentOS Linux version 5.x+.
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Linux kernel version 2.6.28 has been released and available for download. The new version includes following stable and new features:
a] ext4 file system - The ext4 filesystem can support volumes with sizes up to 1 exbibyte and files with sizes up to 16 TiB. ext4 removes ext3 64-bit storage limits and adds other performance improvements.
b] Graphics Execution Manager (GEM) - It is a a modern memory manager specialized for use in device drivers for graphics chipsets. It manages graphics memory, controls the execution context and manages the Non-Uniform Memory Access (NUMA) environment on modern graphics chipsets. The "xf86-video-intel" device driver will feature GEM integration.
c] Other features - Stable USB drivers, KVM, bug fixes and other stuff.
=> Download Linux kernel 2.6.28 here. You may also find our kernel compile tutorial useful.
Canonical the makers of Ubuntu about to introduce a new desktop notification system proposal. New changes should improve the usability of the Linux desktop including desktop notification system for both GNOME and KDE. From the Mark Shuttleworth blog:
The key proposals we are making are that:
* There should be no actions on notifications.
* Notifications should not be displayed synchronously, but may be queued. Our implementation of the notification display daemon will display only one notification at a time, others may do it differently.
That’s pretty much it. There are some subtleties and variations, but these are the key changes we are proposing, and which we will explore in a netbook device with a partner, as well as in the general Ubuntu 9.04 release, schedule gods being willing.
I think new changes looks more like Growl system used in Mac OS X. You can read more about proposal including mockup video that shows new notification system here.
I'd like to send my warmest holiday wishes to all my readers around the globe.
Also, I'd like to thank you for your support and wish to every one a wonderful new year full of great things, success and more freedom using Linux and open source technologies.
VirtualBox is a virtual emulator like VMWare workstation. It has many of the features VMWare has, as well as some of its own.
I really like new Opensource VirtualBox from Sun. It is light on resources. Here is a quick tip - you can convert a VMware virtual machine to a VirtualBox machine using qemu-img utility.
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This is 3rd and the final installment for Apache Chroot Jail for CentOS / RHEL series. Once Apache is configured with mod_chroot, you may need to test and debug problems. This article will provide a few troubleshooting tips.
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Continue reading rest of the Apache 2: RHEL / CentOS Jail Setup series.
