Install PostgreSQL on CentOS 8

Download and install the latest repo RPM from

# dnf install -y

Disable the built-in PostgreSQL module:

# dnf -qy module disable postgresql

Install PostgreSQL:

# dnf install -y postgresql12-server

Optionally initialize the database and enable automatic start:

# /usr/pgsql-12/bin/postgresql-12-setup initdb
# systemctl enable postgresql-12
# systemctl start postgresql-12

Set Up MySQL/MariaDB Master-Slave Replication

MySQL Master-Slave replication allows for data to be automatically copied to multiple computers. Changes are made to the designated “master” node and replicated to one or more designated “slave” nodes for read-only applications.

This tutorial provides step-by-step instructions for setting up a MySQL/MariaDB master-slave database configuration. CentOS 8 and MariaDB 10.5 are used in this example.

Two servers are used in this tutorial, db01 (the master node) and db02 (the slave node). If you already have a database running on the master node, you must dump and restore a backup of the database into the slave node prior to enabling replication.

Read more Set Up MySQL/MariaDB Master-Slave Replication

Install VirtualBox Additions on CentOS 8

Login as root and install packages required for building kernel modules and elfutils-libelf-devel as a prerequisite for the additions.

# dnf install gcc kernel-devel kernel-headers dkms make bzip2 perl elfutils-libelf-devel

From the VirtualBox window, insert the guest-tools CD image.
Devices -> “Insert Guest Additions CD Image”

Mount the virtual CD-ROM drive and install the VirtualBox Additions.

# mkdir /mnt/cdrom
# mount /dev/cdrom /mnt/cdrom
# cd /mnt/cdrom/
# sh ./ --nox11
# reboot

Fix Samba Error – Failed to setup guest info

When starting samba you may receive this error:

smbd[11632]: ../source3/auth/auth_util.c:1382(make_new_ses...guest)
smbd[11632]:   create_local_token failed: NT_STATUS_ACCESS_DENIED
smbd[11632]: ../source3/smbd/server.c:2000(main)
smbd[11632]:   ERROR: failed to setup guest info.

Read more Fix Samba Error – Failed to setup guest info