Although I spend a lot of time on Linux system on my daily work, my main focus is on application side. Yesterday a colleague brought a user login issue to me: he's been working on a secured Oracle Linux server and all of sudden he could not login into the system with his service user … Continue reading How I fixed a Linux user login issue
Month: November 2020
Allow root to login via SSH
Generally for a secured Linux system, the root user is not allowed to login into the server via SSH directly. But from time to time, you might be just working on your own little sandbox and would like to enable direct root ssh login. Here are a couple of sshd configuration keywords you need to … Continue reading Allow root to login via SSH
ORA-16624: broker protocol version mismatch detected
I did an Oracle rolling upgrade for an Oracle DataGuard environment last week and ran into the following error when doing a switchover from one server PROD2 (Oracle SID) to another server PROD1 (Oracle SID) after the upgrade: ORA-16624: broker protocol version mismatch detected This was an interesting problem which was caused by a small … Continue reading ORA-16624: broker protocol version mismatch detected
Getting SCSI controller information with ESXCLI for VMware disks
VMware provides various tools to manage virtual machines. Some are GUI based such as vSphere client, vSphere web client; some are command line based such as vSphere CLI (ESXCLI), PowerCLI. Most of tasks can be easily done via GUI, but sometimes if you need some information to be kept, comand line could be a better … Continue reading Getting SCSI controller information with ESXCLI for VMware disks
Dynamic Service Registration with IPC protocol?
Oracle database services can be registered dynamically to the listener, which then acts as a port mapper for those services. The listener uses the dynamic service information about the database and instance received through service registration. From Oracle Database Net Services Administrator's Guide, "Dynamic service registration is configured in the database initialization file. It does … Continue reading Dynamic Service Registration with IPC protocol?
How does systemd maintain the compatibility with SystemV init scripts?
systemd is a system and service manager for Linux operating systems. When a systemd Linux system starts, systemd runs as first process on boot (as PID 1), and it acts as init system that brings up and maintains userspace services. systemd uses "units" (12 different types) to manage services related to system boot-up and maintenance. … Continue reading How does systemd maintain the compatibility with SystemV init scripts?
Oracle 19c — ORA-28009: connection as SYS should be as SYSDBA or SYSOPER
Before Oracle 19c, we can connect to the database as the user "sys" without giving "as sysdba" if the parameter O7_DICTIONARY_ACCESS is set to TRUE. If this parameter is set to FALSE, you won't connect to the database as the user "sys" without giving "as sysdba". You will get the ORA-280009 if you do so. … Continue reading Oracle 19c — ORA-28009: connection as SYS should be as SYSDBA or SYSOPER
little things to pay attention
Nowdays every one has a busy life and you may need to handle multiple tasks all the time. There are small details we might not pay much attention on them and then as time goes by, they are just forgotten. I was working an Oracle DataGuard setup today. The primary server has been up for … Continue reading little things to pay attention