Sun’s ZFS now has built-in deduplication utilizing a master hash function to map duplicate blocks of data to a single block instead of storing multiple times. What’s deduplication? Deduplication is the process of eliminating duplicate copies of data and mapping duplicate blocks of data to [...]

It’s unfortunate that many programmers are lazy about error messages. Very often, all you get is a cryptic “Error 13“, and you may be lucky to get that: sometimes all you get is an error return that you have to examine the numeric error code yourself with “echo $?“. You [...]

As indicated in title, this request is probably very common for sysadmins. For example, when a Java environment is ready, we need to make sure that JAVA_HOME is globally available for some system accounts, so that they can restart java instance smoothly.

In Unix-like operating systems, Loop device is a pseudo-device that makes a file accessible as a block device. When you mount a file as partition, it would use one loopback device. I faced a loop device related issue this morning, that’s why I create this article to share some ways to bypass limitation [...]

How we can limit the CPU usage of a sepcified process with the CPUlimit utility? Cpulimit is a simple program that attempts to limit the CPU usage of a process. It’s expressed in percentage, not in cpu time. This is useful to control batch jobs, when you don’t want them to eat too much CPU [...]

Here’s a good document on file system analysis. As mentioned from this document: The aptly named UNIX Filesystems: Evolution, Design, and Implementation is only giving a general overview of how things work. Practical File System Design with the Be File System by Dominic Giampaolo is an [...]

This article will describe how to create OpenVZ container in CentOS 5.4. With OpenVZ you can create multiple Virtual Private Servers (VPS) on same hardware machine and running them simultaneously and efficiently. OpenVZ is the open-source branch of Virtuozzo, a commercial virtualization solution widely [...]

The Red Hat Enterprise Linux Life Cycle is designed to reduce the level of change within each major release over time increasing predictability and decreasing maintenance costs. Every major version of Red Hat Enterprise Linux is maintained and supported independently during the life cycle.

What follows for the next few posts is a somewhat edited version of a set of advice I am giving to a Sun team on redesigning a C++ application which was built for MySQL, ported to PostgreSQL, and never performance optimized. It occurred to me that this advice would be generally useful to the community, [...]

Red Hat Enterprise Linux 3 with a 2.4 kernel base uses a single, robust, general purpose I/O elevator. The I/O schedulers provided in Red Hat Enterprise Linux 4, embedded in the 2.6 kernel, have advanced the I/O capabilities of Linux significantly. With Red Hat Enterprise Linux 4, applications can [...]