Improve performance on virtualized RHEL 7 server using tuned

Tuned is a dynamic adaptive system tuning daemon that tunes system settings dynamically depending on usage. You can configure tuned in RHEL 6/7 systems (and CentOS, Oracle Linux etc) using tuned-adm witch is the commandline tool for switching between different tuning profiles.

Installing EPEL Repository to Oracle Linux 7

Extra Packages for Enterprise Linux (or EPEL) is a Repository that holds high quality extra packages that Red Hat Enterprise Linux (RHEL) base distributions (like Oracle Linux 7) does not include. Installation of EPEL in Oracle Linux 7 is simple. We need to download and install an rpm package that EPEL provides.

jdeveloper 12c (12.1.3) is crashing on ubuntu 15.04 with unity

Jdeveloper 12c and especially version 12.1.3 is crashing when used with unity on Ubuntu 15.04. The problem is JAyatana a package for integrate swing applications with unity that is installed by default in 15.04.

Btrfs disable copy on write (cow) for virtual machine disks

In files like vmware virtual disks (vmdk files) is common to disable copy on write (cow) on btrfs filesystems to avoid system slow response due to heavy I/O on disks.

You can verify if a file have disabled the copy on write using lsattr command. If you see a C on the file attributes the copy on write is disabled.

StopWatch with annotations to Profile methods using Spring Aspect Oriented Programming (AOP)

The following example is a way to measure the execution time for methods using Spring Aspect Oriented Programming (AOP).

First we need to create a new annotation:

import java.lang.annotation.*;


@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@Inherited
@Documented
public @interface ProfileExecution 

{

}

Linux convert ext4 to btrfs

Btrfs filesystem tool btrfs-convert can be used for convert ext2/ext3/ext4 to btrfs. Because of the copy on write algorithms of Btrfs it is posible to rollback the conversion even after you start using the converted file system.

The following is sample commands and output from an ext4 conversion to Btrfs in openSUSE 13.1. openSUSE will have Btrfs as the default filesystem from 13.2 which is going to be released next month. Go to openSUSE website for more information:

chris-linux:/home/chris # btrfs-convert /dev/sdb2
/dev/sdb2 is mounted
chris-linux:/home/chris # umount /dev/sdb2
chris-linux:/home/chris # btrfs-convert /dev/sdb2
creating btrfs metadata.
creating ext2fs image file.
cleaning up system chunk.
conversion complete.

Enable jpa 2.0 support on weblogic 10.3.6

Weblogic 10.3.6 has the jars for support jpa 2.0 installed but not enabled. To enable jpa 2.0 support add in the commEnv.cmd (windows) or commEnv.sh (linux) the following: