Oracle, Linux, AWS, Azure, GCP
June 15, 2022 Leave a comment
After installing/starting the tiger VNC server, and connecting using VNC Viewer terminal window is not displayed.
# yum install tigervnc-server
Install xterm:
# yum install xterm
Kill old VNC process and start again:
$ vncserver -kill :1
$ vncserver -geometry 1024x1024
Reconnect using VNC viewer, terminal should be displayed automatically.
April 21, 2022 Leave a comment
There are several ways to do that, I found the simplest (I hope so) and want to share it with you:
0. Create repo file:
# vi /etc/yum.repos.d/google-chrome.repo [google-chrome] name=google-chrome baseurl=https://dl.google.com/linux/chrome/rpm/stable/x86_64 enabled=1 gpgcheck=1 gpgkey=https://dl.google.com/linux/linux_signing_key.pub
1. Enable repo ol7_optional_latest for vulkan dependency:
# yum-config-manager --enable ol7_optional_latest
2. Install google-chrome-stable package:
# yum install google-chrome-stable -y
3. Run:
$ google-chrome
Or in the background:
$ google-chrome &
The window will come up in VNC or X Window whichever you’ve configured before.
March 22, 2022 Leave a comment
There are several ways to fulfill the same task, I am providing one of them.
# uname -r 5.4.17-2036.101.2.el7uek.x86_64
2. Find all available kernels in your system and locate their index number:
# grubby --info=ALL index=0 kernel=/boot/vmlinuz-5.4.17-2036.101.2.el7uek.x86_64 args="ro console=tty1 console=ttyS0,115200n8 earlyprintk=ttyS0,115200 rootdelay=300 numa=off transparent_hugepage=never net.ifnames=0" root=/dev/mapper/rootvg-rootlv initrd=/boot/initramfs-5.4.17-2036.101.2.el7uek.x86_64.img title=Oracle Linux Server 7.9, with Unbreakable Enterprise Kernel 5.4.17-2036.101.2.el7uek.x86_64 index=1 kernel=/boot/vmlinuz-3.10.0-1160.42.2.el7.x86_64 args="ro console=tty1 console=ttyS0,115200n8 earlyprintk=ttyS0,115200 rootdelay=300 numa=off transparent_hugepage=never net.ifnames=0" root=/dev/mapper/rootvg-rootlv initrd=/boot/initramfs-3.10.0-1160.42.2.el7.x86_64.img title=Oracle Linux Server 7.9, with Linux 3.10.0-1160.42.2.el7.x86_64 index=2 kernel=/boot/vmlinuz-0-rescue-d3dd3af16fd242cebb997c6041d68ad3 args="ro console=tty1 console=ttyS0,115200n8 earlyprintk=ttyS0,115200 rootdelay=300 numa=off transparent_hugepage=never net.ifnames=0" root=/dev/mapper/rootvg-rootlv initrd=/boot/initramfs-0-rescue-d3dd3af16fd242cebb997c6041d68ad3.img
3. Check currently loaded kernel index using grubby tool (actually, we could find the same from 1st and 2nd steps, but let’s do one more time):
# grubby --default-index 0
4. Change the default kernel, in my case I want to set it to vmlinuz-3.10.0-1160.42.2.el7.x86_64 and it’s index number is 1:
# grubby --set-default 1
5. Reboot the system and check the kernel again:
# reboot # uname -r 3.10.0-1160.42.2.el7.x86_64
December 17, 2021 Leave a comment
Yes, it can be changed without impacting the business operations.
Oracle source: Doc ID 2269728.1
RHEL source: https://access.redhat.com/solutions/437043
========================Additional information========================
Additional explanation, why you may need to change that value.
Alert log shows:
ORA-27090: Unable to reserve kernel resources for asynchronous disk I/O Linux-x86_64 Error: 2: No such file or directory Additional information: 3 Additional information: 128 Additional information: 139817340277512
The problem is caused by a lower than recommended value for aio-max-nr. The current value is 1048576, but recommended is 3145728.
Set fs.aio-max-nr to 3145728 in /etc/sysctl.conf.
# grep fs.aio-max-nr /etc/sysctl.conf fs.aio-max-nr = 3145728
Make a new value effective:
# sysctl -p /etc/sysctl.conf
Verify the new value:
# sysctl -a|grep fs.aio-max-nr fs.aio-max-nr = 3145728
June 19, 2021 Leave a comment
Intro:
This blog post belongs to my student at Business and Technology University Ivane Metreveli, thank you Ivane for participating in this project.
2. Set Name of the Virtual Machine and select operation system as follows, click Next
3. Select appropriate RAM amount, 3GB RAM is recommended for normal processing, click on Next button and jump to next step
4. Now, Select Create a virtual hard disk now option and click Create button
5. Select VDI(virtualbox Disk image)
6. Select Dynamically allocated if you don’t want take hard disk space immediately
7. Select file size (disk size for VB) and the location, click Create button to finish virtual machine creation process
8. Virtual machine is already is created. Before we open/start VM, we load iso file in the machne, click Settings and follow me
9. Navigate to Storage and click CD icon, on the right side of the window, under attributes, click CD icon and add virtual machine’s .iso file.
10. After that, you can click start button
11. Select .iso files or click folder icon and open folder where .iso file is located, select it and click start
12. Next step is OS installation process, here you select Install Oracle linux 7.6 and click enter to start installation process:
13. Select system language and click continue
14. Select installation destiantion
15. Select the disk where you want to install system. You can select virtual disk, that you have created in the previous step or add a new one. Select disk and click Done button;
16. Now all parameter is ready. Click Begin Installation and wait for finishing the process
17. Set password and click Done
18. Installation is in progress, need to wait more
19. Installation proess is finished, click Roboot button and move to the next step:
20. Installation is finised now, you can start working with Oracle Linux:
May 20, 2021 2 Comments
Problem:
After checking if flashgrid-clan package was installed, got this error:
error: rpmdb: BDB0113 Thread/process 2884/140438918064192 failed: BDB1507 Thread died in Berkeley DB library
error: db5 error(-30973) from dbenv->failchk: BDB0087 DB_RUNRECOVERY: Fatal error, run database recovery
error: cannot open Packages index using db5 - (-30973)
error: cannot open Packages database in /var/lib/rpm
error: rpmdb: BDB0113 Thread/process 2884/140438918064192 failed: BDB1507 Thread died in Berkeley DB library
error: db5 error(-30973) from dbenv->failchk: BDB0087 DB_RUNRECOVERY: Fatal error, run database recovery
error: cannot open Packages database in /var/lib/rpm
package flashgrid-clan is not installed
Reason:
If you see rpmdb errors during package management (rpm, yum), it means that the RPM database is corrupted.
Solution:
# mkdir /var/lib/rpm/backup # cp -a /var/lib/rpm/__db* /var/lib/rpm/backup/ # rm -f /var/lib/rpm/__db.[0-9][0-9]* # rpm --quiet -qa # rpm --rebuilddb # yum clean all
May 9, 2021 Leave a comment
I have used this command many times, but the interval between each usage is so big that I almost always forget the syntax.
So here it is:
# du -a / | sort -n -r | head -n 5 51190272 / 37705424 /root 33040524 /root/apache-tomcat-7.0.53 32802516 /root/apache-tomcat-7.0.53/logs 32802440 /root/apache-tomcat-7.0.53/logs/catalina.out
January 19, 2021 Leave a comment
Life is too short, that’s why it’s mandatory to use shortcuts… Instead of typing frequently used ssh client options such as port, user, hostname, identity-file and so on, you can save that information in sshd config file and then access it with defined alias.
/etc/ssh/ssh_config~/.ssh/config same as $HOME/.ssh/configInstead of connecting to the server everytime using the following command:
# ssh root@95.80.12.10 -i ~/.ssh/my_id_rsa
Save the following entries in ~/.ssh/config file:
# vim ~/.ssh/config
Host my_db
HostName 95.80.12.10
IdentityFile ~/.ssh/my_id_rsa
User root
And connect to the server using this simple way:
# ssh my_db
For other options check https://linuxize.com/post/using-the-ssh-config-file/
August 1, 2020 Leave a comment
There are several ways to identify that, I will suggest one of them using rpm -qf, that finds out what package a file belongs to:
Oracle Linux:
# rpm -qf /etc/redhat-release
oraclelinux-release-7.8-1.0.7.el7.x86_64
RHEL:
# rpm -qf /etc/redhat-release
redhat-release-server-7.8-2.el7.x86_64
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