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For Oracle Automatic Storage Manager (ASM) to use disks, it needs to be able to identify the devices consistently and for them to have the correct ownership and permissions. In Linux you can use ASMLib to manage these tasks, but it is seen as an additional layer of complexity and has never really gained any popularity. Instead, many people use the Linux device manager "udev" to perform these tasks. This article presents a brief overview of setting up udev rules with respect to disks for use with ASM in Oracle 11g. The examples are all done using Oracle Linux 5, 6 and 7, so they will be consistent with RHEL and CentOS 5, 6 and 7. Background Essentially, what udev does is apply rules defined in files in the "/etc/udev/rules.d" directory to the device nodes listed in the "/dev" directory. The rules can be defined in a variety of ways, but what we need to do is identify the device and say what we want udev to do with it. In this case I know all my disk...

When you first create a new Ubuntu 16.04 server, there are a few configuration steps that you should take early on as part of the basic setup. This will increase the security and usability of your server and will give you a solid foundation for subsequent actions. Step.1 — Root Login To log into your server, you will need to know your server's public IP address. You will also need the password or, if you installed an SSH key for authentication, the private key for the "root" user's account. If you are not already connected to your server, go ahead and log in as the root user using the following command (substitute the highlighted word with your server's public IP address): ssh root@your_server_ip Complete the login process by accepting the warning about host authenticity, if it appears, then providing your root authentication (password or private key). If it is your first time logging into the server with a password, you will also be prompted to change the...

Privilege separation is one of the fundamental security paradigms implemented in Linux and Unix-like operating systems. Regular users operate with limited privileges in order to reduce the scope of their influence to their own environment, and not the wider operating system. A special user, called  root , has "super-user" privileges. This is an administrative account without the restrictions that are present on normal users. Users can execute commands with "super-user" or "root" privileges in a number of different ways. In this article, we will discuss how to correctly and securely obtain  root  privileges, with a special focus on editing the  /etc/sudoers  file. We will be completing these steps on an Ubuntu 16.04 server, but most modern Linux distributions should operate in a similar manner. This guide assumes that you have already completed the  initial server setup  discussed here. Log into your server as regular, non-root user and contin...