IPVS (IP Virtual Server) implements transport-layer load balancing inside the Linux kernel, so called Layer-4 switching. IPVS running on a host acts as a load balancer at the front of a cluster of real servers, it can direct requests for TCP/UDP based services to the real servers, and makes services of the real servers to appear as a virtual service on a single IP address.

IPVS is commonly used for DNS load balancing as well as other things.

Minon's job is to watch log files on the filesystem and send their contents to a syslog server [either local or remote] as they are updated. He's a helpful little bugger.

And since this is perl, I thought, "why not throw in some regex support?" So if you're so inclined, you can tell minion to only send lines that match a certain pattern of your choosing.

Features:

* runs on any Posix platform with Perl 5.005+ and File::Tail
* capable of tailing multiple files simultaneously using a threaded algorithm
* daemonizes itself on startup and can be run from a startup script
* full regular expression support for pre-filtering logs before sending them
* log levels, facility and application name are configurable

OpenVZ is an Operating System-level server virtualization solution, built on Linux. OpenVZ creates isolated, secure virtual environments — VEs (otherwise known as virtual private servers, or VPSs) on a single physical server enabling better server utilization and ensuring that applications do not conflict. Each VE performs and executes exactly like a stand-alone server; VEs can be rebooted independently and have root access, users, IP addresses, memory, processes, files, applications, system libraries and configuration files. See Documentation » Technology for more information.

The OpenVZ project is an open source community project supported by SWsoft and is intended to provide access to the code and ultimately for the open source community to test, develop and further the OS virtualization effort. It is also a proving ground for new technology that may evolve into the Virtuozzo™ product offering. We encourage the community to access, use, develop and comment on the software and references on this site.

A suite of Unix command-line tools and a server designed to remotely administer the file systems of multiple Unix machines. For Mac OS X, there's also a graphical interface.

At its core, radmind operates as a tripwire. It is able to detect changes to any managed filesystem object, e.g. files, directories, links, etc. However, radmind goes further than just integrity checking: once a change is detected, radmind can optionally reverse the change.

Each managed machine may have its own loadset composed of multiple, layered overloads. This allows, for example, the operating system to be described separately from applications.

shush runs a command and optionally reports its output by mail based on the command's output, output size, exit code and/or duration.

It is a powerful wrapper around cron jobs which if properly configured will allow you to never get emails from cron jobs unless you need to see them!

shmux is a program for executing the same command on many hosts in parallel. For each target, a child process is spawned by shmux, and a shell on the target obtained one of the supported methods: rsh, ssh, or sh. The output produced by the children is received by shmux and either output in turn to the user in an easy to read format, or written to files for later processing, making it well suited for use in scripts.

shmux is a very powerful tool solving a simple problem in a generic way.

Ever been disconnected from your ssh session while in the middle of something? Ever wished there was a way to reconnect to that lost ssh session? Screen is for you..

Screen is a full-screen window manager that multiplexes a physical terminal between several processes. In fact, when you execute screen, you can imagine that you turned on another screen to the server that you're working on. You then execute your process on that virtual screen, detach your connection from it and return, whenever you please, to that screen in order to continue working.

Screen is a full-screen window manager that multiplexes a physical terminal between several processes, typically interactive shells. Each virtual terminal provides the functions of the DEC VT100 terminal and, in addition, several control functions from the ANSI X3.64 (ISO 6429) and ISO 2022 standards (e.g., insert/delete line and support for multiple character sets). There is a scrollback history buffer for each virtual terminal and a copy-and-paste mechanism that allows the user to move text regions between windows. When screen is called, it creates a single window with a shell in it (or the specified command) and then gets out of your way so that you can use the program as you normally would. Then, at any time, you can create new (full-screen) windows with other programs in them (including more shells), kill the current window, view a list of the active windows, turn output logging on and off, copy text between windows, view the scrollback history, switch between windows, etc. All windows run their programs completely independent of each other. Programs continue to run when their window is currently not visible and even when the whole screen session is detached from the users terminal.

daemontools is a collection of tools for managing UNIX services.

supervise monitors a service. It starts the service and restarts the service if it dies. Setting up a new service is easy: all supervise needs is a directory with a run script that runs the service.

multilog saves error messages to one or more logs. It optionally timestamps each line and, for each log, includes or excludes lines matching specified patterns. It automatically rotates logs to limit the amount of disk space used. If the disk fills up, it pauses and tries again, without losing any data.

A less encumbered version is available at http://smarden.org/runit/

Nagios is a host and service monitor designed to inform you of network problems before your clients, end-users or managers do. It has been designed to run under the Linux operating system, but works fine under most *NIX variants as well (We have run it on Solaris 2.8 and now Solaris 10). The monitoring daemon runs intermittent checks on hosts and services you specify using external "plugins" which return status information to Nagios. When problems are encountered, the daemon can send notifications out to administrative contacts in a variety of different ways (email, instant message, SMS, page etc.). Current status information, historical logs, and reports can all be accessed via a web browser. A wap interface is also available.

DTrace is a comprehensive dynamic tracing facility that is built into the Solaris OS. DTrace can be used by administrators and developers, and can safely be used on live production systems. DTrace enables you to examine the behavior of user programs as well as the behavior of the operating system. Users of DTrace can create custom programs with the D scripting language. Custom programs provide the ability to dynamically instrument the system. Custom programs provide immediate, concise answers to specific questions about the behavior of particular applications.