When you must restore the database the same directory structure is not always available. If you have a database containing 1000s of datafiles it can be very tedious to setup the set newname commands for all the datafiles. Using sqlplus we can extract the information we need into a file which can then be easily modified and executed as an RMAN script to complete the task. Oracle 11g New Command - 'SET NEWNAME FOR DATABASE' Starting from 11.2, we can use SET NEWNAME FOR DATABASE clause to … [Read more...] about RMAN: SET NEWNAME Command Using SQL
Nohup Command Examples – Runs a Command that Keeps Running after You Log Out
The nohup utility executes a command line such that the command keeps running after you log out. In other words, nohup causes a process to ignore a SIGHUP signal. Depending on how the local shell is configured, a process started without nohup and running in the background might be killed when you log out. Syntax for running nohup command The basic command sytax for running a nohup command is as follows: # nohup command_with_options & Any output from your job will be redirected to a file … [Read more...] about Nohup Command Examples – Runs a Command that Keeps Running after You Log Out
How to capture a vmcore from a KVM or RHEV guest
For a kernel panic, kdump (CentOS/RHEL 5 and above) or netdump/diskdump (CentOS/RHEL 4 and earlier) can be configured within the guest just like on a bare metal system. In the event those services cannot capture a vmcore, such as the guest going unresponsive, qemu-kvm's monitor functionality can be used. The commands are slightly different for qemu-kvm/libvirt RHEL KVM guests and for RHEV guests: For qemu-kvm/libvirt RHEL KVM guests: # virsh dump domain-name /tmp/dumpfile --memory-only … [Read more...] about How to capture a vmcore from a KVM or RHEV guest
How to disable firewalld and nftables and use iptables instead in CentOS/RHEL 8
CentOS/RHEL 8 now uses iptables as the default packet filtering framework, and is also used by firewalld. But if you try starting iptables, it would fail by default. Follow the steps outlined below to disable firewalld and nftables and enable iptables instead. 1. Install the iptables-services package: # dnf install iptables-services 2. Disable nftables and firewalld: # systemctl disable nftables firewalld Removed /etc/systemd/system/multi-user.target.wants/nftables.service. Removed … [Read more...] about How to disable firewalld and nftables and use iptables instead in CentOS/RHEL 8
How to add an Ethernet connection using nmcli in CentOS/RHEL 7
Question: How to use nmcli to add an Ethernet connection with manual or via DHCP configuration? The NetworkManager command line tool, nmcli, provides those who prefer to use the command line way to configure networking by controlling NetworkManager. It is installed along with NetworkManager. Installing NetworkManager Use nmcli with the object connection and command add. (This can be abbreviated to con add). The first step should be to have the latest version of NetworkManager package, … [Read more...] about How to add an Ethernet connection using nmcli in CentOS/RHEL 7
How to set the order to load certain modules in CentOS/RHEL 7 and 8
If you want to load modules that have dependencies then you can use the modprobe command. It will automatically resolve the dependencies and load the modules. Here are three ways to accomplish loading modules at boot automatically: 1. Using systemd-modules-load.service (Recommended) Use systemd-modules-load.service to load the modules during boot. 1. Add a file in /etc/modules-load.d/[name].conf containing module names. It will read the lines in order and load the modules … [Read more...] about How to set the order to load certain modules in CentOS/RHEL 7 and 8
How to configure initrd / initramfs to including kernel modules in CentOS/RHEL
The method for including kernel modules in the initrd / initramfs varies based on RHEL version. In all examples replace [kernel module] with the module name, not including .ko. For CentOS/RHEL 4 and 5 Three methods can be used to include a kernel module in the initial RAM disk: 1. Use the --withM option when manually building the ram disk with mkinitrd: # mkinitrd --with=[kernel module] /boot/initrd-$(uname -r).img $(uname -r) 2. For storage-related modules put an alias in … [Read more...] about How to configure initrd / initramfs to including kernel modules in CentOS/RHEL
How to configure systemd.path to trigger an event when any changes made to a directory
What is systemd.path systemd.path works similar to auditd in earlier versions with extra features as triggering an event or a run a script when a change is made to file or directory. From the man page of systemd.path: A unit configuration file whose name ends in ".path" encodes information about a path monitored by systemd, for path-based activation. Path files must include a [Path] section, which carries information about the path(s) it monitors. How to configure systemd.path … [Read more...] about How to configure systemd.path to trigger an event when any changes made to a directory
Script to monitor RMAN Backup and Restore Operations
RMAN is designed to complete a backup or restore as quikly and efficiently as possible. But if a job takes longer than expected to complete it can be confusing trying to determine: What precisely is RMAN doing at any particular time? Is RMAN hung or just slow? How far into the backup/restore has it got? How much more work is there to go? Knowing just how much processing has been done so far is often crucial when trying to decide whether or not to wait for job completion. RMAN … [Read more...] about Script to monitor RMAN Backup and Restore Operations
Oracle RMAN Backup Shell Script Example
Pre-requisites 1. Create a catalog database (rmancat) if one does not exist. (With additional UNDO-, USERS- and TEMP-tablespaces) 2. Configure SQL*Net to handle the catalog (rmancat) and the 'target' database connections. 3. Create a user 'RMAN' in the catalog database. SQL> create user rman identified by rman default tablespace USERS quota unlimited on users temporary tablespace TEMP; SQL> grant recovery_catalog_owner to rman; 4. Create the RMAN-catalog in the … [Read more...] about Oracle RMAN Backup Shell Script Example