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[root@foo block]# strace -f -s2048 -eopen fdisk -l |& grep /sys/dev/block/
open("/sys/dev/block/8:0", O_RDONLY|O_CLOEXEC) = 5
open("/sys/dev/block/8:0", O_RDONLY|O_CLOEXEC) = 5
open("/sys/dev/block/253:0", O_RDONLY|O_CLOEXEC) = 5
open("/sys/dev/block/253:0", O_RDONLY|O_CLOEXEC) = 5
open("/sys/dev/block/253:1", O_RDONLY|O_CLOEXEC) = 5
open("/sys/dev/block/253:1", O_RDONLY|O_CLOEXEC) = 5
open("/sys/dev/block/253:2", O_RDONLY|O_CLOEXEC) = 5
open("/sys/dev/block/253:2", O_RDONLY|O_CLOEXEC) = 5

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- Surveying the Linux Kernel, let's look more at /proc, /sys, and device files. Virtual Filesystems that we talked about proc and sysfs that means these virtual filesystems don't store their contents on a disk, more accurately they generate their contents when you ask for it. When you cat a file in proc or sys, there's some corresponding function in the kernel that's called to generate the contents. These are not RAM-based filesystems. RAM filesystems store their contents in RAM.

Virtual filesystems generate their contents when you ask for it, like callback functions. proc got its name from process, and the proc filesystem is normally mounted on /proc. That's done early on in the boot process. proc contains lots of process information, as can be expected, plus lots, lots more. This essentially is information about the state of the kernel. A lot of utilities get information about the kernel from the proc directory.

The ps command, process status, gets its information from the proc directory. A real important

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[root@foo block]# cat /proc/cmdline 
BOOT_IMAGE=/vmlinuz-3.10.0-327.4.4.el7.x86_64 root=/dev/mapper/centos-root ro rd.lvm.lv=centos/swap vconsole.font=latarcyrheb-sun16 rd.lvm.lv=centos/root crashkernel=auto vconsole.keymap=us rhgb quiet LANG=en_US.UTF-8

[root@foo block]# cat /proc/partitions 
major minor  #blocks  name

  11        0    1048575 sr0
   8        0  976762584 sda
   8        1    2097152 sda1
   8        2  973832192 sda2

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The issue may have to do with the installed version of libsolv not supporting bzip2 compression. Like me, you may not have the most recent version being installed because setting priorities in the repo config files.

Failed to open: /var/cache/dnf/x86_64/7/x86_64/7/epel/...xml.bz2
See bug report 1258416.

libsolv-0.6.14-1.el7 has been pushed to the Fedora EPEL 7 stable repository. If problems still persist, please make note of it in this bug report.
The libsolv installed from the CentOS base repository is 0.6.11-1.el7, but the one in epel is 0.6.14-1.el7.

yum --showduplicates --disablerepo=base list libsolv
Installed Packages

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from __future__ import print_function

import boto3
import json
import logging

from base64 import b64decode
from urllib2 import Request, urlopen, URLError, HTTPError

import json

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REMEMBER !!! 
TO CONNECT TO A REMOTE HOST IN THE OTHER VPC, WE'D NEED TO OPEN UP THE CORRESPONDING PORT ON THE VPN-TUNNEL SERVER SECURITY GROUP ON THE SAME SIDE AS WELL AS ONLY THEN THE TUNNEL INSTANCE WILL ALLOW THE FLOW OF TRAFFIC TO THE OTHER SIDE. REPEAT THE SAME STEPS FOR THE OTHER SIDE TOO.

MUM - TUNNEL SERVER - sg

TCP 22 0.0.0.0/0
 
TCP
 
51

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mkfifo /tmp/mysql-pipe
mysql mydb </tmp/mysql-pipe &
(
  echo "LOCK TABLES mytable READ ;" 1>&6 
  echo "Doing something "
  echo "UNLOCK  tables;" 1>&6
) 6> /tmp/mysql-pipe

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MASTER


MariaDB [(none)]> create user 'replication'@'%'identified by 'password';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> grant replication slave on *.* to replication
    -> ;
Query OK, 0 rows affected (0.00 sec)

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    1  yum install -y firewalld
    2  systemctl enable firewalld 
    3  systemctl start firewalld 
    4  systemctl status firewalld 
    5  firewall-cmd --get-default-zone
    6  firewall-cmd --list-zones
    7  firewall-cmd --list-zone
    8  firewall-cmd list-zone
    9  firewall-cmd list-zones
   10  firewall-cmd

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At the end these are steps you need to have a docker server with OverlayFS as backend storage on AWS/EC2

Fire up an 'ubuntu 14.04' server on AWS/EC2
Upgrade kernel to 3.18
Install Docker on server
Create an EBS volume
Attach new volume to created server
Create a file system on volume: 
6.1. Connect to your instance and run lsblk to find available disk devices and their mount points. 
6.2. From the result of lsblk command, choose device that is attached, but not been mounted yet (e.g. xvdf, ...). devicename would be the selected device with a /dev/ as a prefix (e.g. /dev/xvdf,...)