FLUSH flush_option [,flush_option] You should use the FLUSH command if you want to clear some of the internal caches MySQL uses. To execute FLUSH, you must have the reload privilege.flush_option can be any of the following:   HOSTS Empties the host cache tables. You should flush the host tables if some of your hosts change [...]

The first command we’ll look at is the “df” command. It comes bundled with all distributions of Linux. “df” stands for “disk free”. It gives you a reading of the state of all your partitions. It gives you the total disk space, the used space, the space available, and then the percentage of space being [...]

The ssh program can  be used for monitoring remote hots. The system admin can also execute commands from his desktop which can be executed at remote servers. This is a cool facility of ssh. We can do much more on SSH. root@admin:~ # ssh root@www ‘df -h’ Filesystem Size Used Avail Use% Mounted on /dev/ubda 3.5G 2.1G [...]

This warning means that at least one searcher hadn’t yet finished warming in the background, when a commit was issued and another searcher started warming. This can not only eat up a lot of ram (as multiple on deck searches warm caches simultaneously) but it can can create a feedback cycle, since the more searchers [...]

There are plenty of system optimizers and registry cleaners out there, but today I will tell you about a great free one called CCleaner.  It is very simple to use and can drastically increase your computers performance. CCleaner can delete all unnecessary temporary files from most browsers including IE, Firefox, Google Chrome and Opera as [...]

Here are some ideas, how you can monitor the database performance of your MySQL installation. Monitoring is always an iterative and continuous process. You need to learn what patterns are OK for your database and what are the signs of slight problems or even dangerous situations. Below are the main items you can use to [...]

This article uses postfix as the mail transport agent (MTA), as opposed to sendmail, the default MTA for CentOS. Dovecot is used to allow users to access their email by either imap or pop protocols. We assume a domain name of example.com which should be changed by the reader and can be either a real [...]

This allows full access through our firewall to certain trusted sources (host PCs). Now we’ll look at how we can filter against protocols and ports to further refine what incoming packets we allow and what we block. Before we can begin, we need to know what protocol and port number a given service uses. For [...]

I can use tcpdump to verify that encryption is working. Here is what a plain unencrypted POP mail session looks like. This is an abbreviated example showing only the initial three-way TCP handshake. You can do this yourself by firing up tcpdump, then checking mail. Ctrl+C stops it: # tcpdump port 110 15:04:49.050227 windbag.34348 > [...]

Replication enables data from one MySQL database server (called the master) to be replicated to one or more MySQL database servers (slaves). Replication is asynchronous – your replication slaves do not need to be connected permanently to receive updates from the master, which means that updates can occur over long-distance connections and even temporary solutions [...]

Virtual Hosting allow web servers to host more than one website on a sing machine. This is how sharing hosting works. I become pretty handy as well while develloping different web project on the same machine and allows you to access to your local repository using addresses such as http://dev.mysite.com instead of http://localhost/~myuser/myproject/ :) . [...]