Create software RAID1

# create raid1 using /dev/sda1 and /dev/sdb1
mdadm --create /dev/md0 --level=mirror --raid-devices=2 /dev/sd[ab]1

# List raid1 info
mdadm --detail /dev/md0

# check raid config in /dev/sd[ab]
mdadm -E /dev/sd[ab]

# Then install CentOS on /dev/md0

Refer to: 

1. Setting up RAID 1 (Mirroring) using ‘Two Disks’ in Linux – Part 3 
   

Compile and Install Python 3.8

Install Python 3.8 refer to:

How to Build Python From Source Code

wget https://www.python.org/ftp/python/3.8.4/Python-3.8.4.tgz

# For apt-based systems (like Debian, Ubuntu, and Mint)
$ sudo apt-get install -y make build-essential libssl-dev zlib1g-dev \
       libbz2-dev libreadline-dev libsqlite3-dev wget curl llvm \
       libncurses5-dev libncursesw5-dev xz-utils tk-dev

# For yum-based systems (like CentOS)
$ sudo yum -y groupinstall "Development Tools"
$ sudo yum -y install gcc openssl-devel bzip2-devel libffi-devel

$ tar xvf Python-3.8.4.tgz
$ cd Python-3.8.4

$ ./configure --enable-optimizations --with-ensurepip=install

$ make -j 8

$ sudo make altinstall

$ python3.8 --version
Python 3.8.4

# To run the test suite, type the following command:
$ python3.8 -m test

Install/Remove X Desktop System

Refer to 

• Installing / Removing GUI on Centos 7, RedHat 7 (RHEL) Minimal Install and Enable Remote Desktop 
  

How to install miniconda and using environment

Refer to:

•  Using QGIS from Conda 
• Install Miniconda or Anaconda 
  

For example,

conda create --name qgis_stable

To use an environment, you need to activate it.

conda activate qgis_stable

Your terminal prompt will show you the active environment.

(qgis_stable) aneto@oryx:~/miniconda3$

To deactivate the current environment, you run

conda deactivate