Showing posts with label Openstack. Show all posts
Showing posts with label Openstack. Show all posts

Comparing AWS, Azure and Redhat exams

In last couple of years I’ve given certification exams of multiple cloud providers. While AWS and Azure exams are more theoretical and based on multiple choice questions. Redhat Openstack is practical lab exam. In this article I’ll be discussing the pros and cons of the different exam patterns.
AWS
Passed AWS CSA – Associate and Professional
Pros:-
  • You can refer to any question any time you want during the exam.
  • Exam tests you on a wide range of topic.
  • Even if you have made mistakes in the beginning you can recover by reviewing the questions later.
  • No datasheet type questions like “How much RAM does C3.Xlarge offers?”
  • You get 1 Year free tier which is great to learn about AWS.
Cons:-
  • Exams are expensive in comparison to Microsoft Azure (at least in India)
  • In many question it just tests your reading speed.
  • No version, so you don’t know if you should answer as per recent announcement or old method available.
Azure
Passed Architecting Microsoft Azure Solutions.
Pros:-
  • Azure exams are not very expensive in comparison to AWS or Red Hat.
  • Exam tests you on a wide range of topic.
  • Even if you have made mistakes in the beginning you can recover by solving correctly other answers in later sections.
Cons:-
  • No version, so you don’t know if you should answer as per recent announcement or old method available.
  • It’s a race against time.
  • The most insane thing I found in the exam is that with each case study you get 5 to 6 questions. But, for about 2 to 3 questions in that case study you can’t refer back to case study. I don’t understand why Microsoft expects you to remember the whole 2 page case study.
  • 30 days free tier is too less to know about azure.
Update:- Azure is now(Oct-17) offering 12 months free trial.
Redhat Openstack
Passed  RHCSA in Redhat Openstack
Pros:-
  • The difficulty level of the exam is medium.
  • You generally get questions on tasks which you will be doing in real life.
  • You get only 15-20 questions (tasks) and even if someone knows those questions beforehand he will have to do the tasks practically to pass the exam. So even if anyone has dumps, they are useless.
  • It has versioning so you know you have to answer as per Redhat Openstack version 6 or 8.
  • Can play with Redhat Openstack by installing it in your desktop or laptop. Good Learning!
Cons:-
  • Exams are expensive in comparison to Microsoft Azure.
  • If you have made a mistake at the beginning or in the middle of exam chances are you will mess up the whole exam or waste lot of time correcting it.
  • If your machine doesn’t work properly you may lose time. But generally examiners take care of this.
In the end, I’d like to say that professional exams should not be like your college entrance exams where they mostly test your reading speeds and cramming abilities. But it’s OK for them as the undergrad and grad have limited practical experience.
Professional exams should be more practical, that makes you sure that if a person has cleared the exam, he definitely know how to do that stuff in real life.
If you want to know how to prepare for these exams refer my post for AWS , Azure and Redhat Openstack .

OpenStack Crash Course - Neutron

Openstack Neutron is the networking service.  It is similar to AWS VPC or Azure VNET.
  • Manual and automatic management of networks and IP addresses.
  • Distinct networking models for different applications and user groups.
  • Flat networks (VLAN’s) for separating servers and traffic.
  • Supports both Static IP addresses and DHCP.
  • Floating IP addresses for dynamic rerouting to resources on the network.
  • Software-defined networking (SDN), OpenFlow, for multi-tenancy and scalability.
  • Management of intrusion detection systems (IDS), load balancing, firewalls, VPN’s, etc.

OpenStack Crash Course - Glance

Glance is image service of OpenStack. It’s similar to AWS AMI and Azure VM Images.
  • OpenStack Image Service for discovery, registration, and delivery of services for disk and server images
  • Template-building from stored images
  • Storage and cataloging of unlimited backups
  • REST interface for querying disk image information
  • Streaming of images to servers
  • VMware integration, with vMotion Dynamic Resource Scheduling (DRS) and live migration of running virtual machines
  • All OpenStack OS images built on virtual machines
  • Maintenance of image metadata
  • Creation, deletion, sharing, and duplification of images

OpenStack Crash Course - Nova

Openstack Nova is the equivalent of AWS EC2 instances or Azure VMs.
  • It’s an Infrastructure as a Service (IaaS) offering.
  • Provides management and automation of pools of Virtual Machines
  • Bare metal and high-performance computing (HPC) configurations
  • It supports KVM, VMware, and Xen hypervisor virtualization
  • Hyper-V and LXC containerization
  • Python-based with various external libraries: Eventlet for concurrent programming, Kombu for AMQP communication, SQLAlchemy for database access, etc.
  • Designed to scale horizontally on standard hardware with no proprietary hardware or software requirements
  • Inter operable with legacy systems

Solved: How to calculate number of available IPs in a Subnet

Many people are confused about how many usable IPs you can get in a subnet and how to calculate it.
So here I am giving you a simple way to calculate it.
Here is the formula.
Maximum Number of IPs = 2**(32 - netmask_length)
Let’s say you have subnet mask  /28 then the maximum number of IPs you can have is
Maximum Number of IPs= 2**(32-28) = 2**(4) = 2*2*2*2 = 16
So you can have max 16 IPs in a  /28 subnet.
First and last IP of subnet is reserved for Network Address and Broadcast Address. So you are left with only 14 IPs in normal networks.
But, generally cloud providers like AWS, Azure etc. reserve 5 IPs instead of 2 IPs in each subnet . Thus, the the usable IPs available for you in AWS or Azure for /28 subnet will be 11.
Similarly, you can calculate the usable IPs in each subnet when working on cloud .
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How to prepare for EX210 – RHCSA in Red Hat OpenStack Exam

Red Hat Certified System Administrator in Red Hat OpenStack exam tests the Openstack management skills of candidate.  Before you start preparing for this exam you should understand basic Linux. Redhat recommends skills of at least the level of RHCSA-RHEL. And this level is important as it’s a lab exam and you have to answer the questions by doing them practically.
If you are a newbie on linux  and want to quickly master linux you can check Learn Linux course on Udemy.
Here I am listing few Linux commands and topics which you should know before sitting for the Redhat Openstack exam.
  1. Comfortable with vi/vim editor. You should know how to edit a file because you will have to edit the configuration file for starting the openstack installation.
  2. Know how to navigate in linux and view files using commands like cd , ls, more, cat etc.
  3. You can use commands like cp, mv to copy and move or rename a file.
  4. Should understand how a repository is created in linux. The repo file is generally saved in /etc/yum.repos.d .
  5. Know how to update the patches in linux using YUM or rpm tools.
  6. Understand basic networking using commands like “ifconfig -a” and “ip addr” . Network configuration files are generally stored in /etc/sysconfig/network-scripts directory. Check how to configure IP.
  7. Check the files where the server names are saved like /etc/hosts .
  8. Understand how the LVM(Logical Volume Manager) works in Linux. For details refer free LVM crash course .
  9. How to start/stop and enable/disable services in linux.
  10. How to sftp and ssh to and from the openstack server.
If you are comfortable up to the above mentioned level of Linux. You can start checking the different components of openstack. Below is listing of few components for which questions will be asked in exam.
  1. Compute (Nova)
  2. Networking (Neutron)
  3. Block storage (Cinder)
  4. Identity (Keystone)
  5. Image (Glance)
  6. Object storage (Swift)
  7. Dashboard (Horizon)
  8. Orchestration (Heat)
  9. Heat(Orchestration)
In exam, you can do installation in two ways. Either you install each component manually or use packstack package/tool to do the installation. If you are new to openstack I recommend using packstack. For packstack installation you will generate a file and modify it as per the requirement mentioned in exam questions. Once the file is ready give it as input to packstack. Packstack will do all the installations for you.
Once the installation is done you can use CLI or GUI for doing further questions in exam. If you are new to Openstack, GUI is best option. It is good and gives you a graphical overview of what you are doing.
Some of the questions you can expect in exam post installation are:-
  1. Create Public and Private subnets
  2. Create Users and Projects
  3. Launch instance
  4. Create Volumes
  5. Attach volumes to instance.
Tip: The exercises given at the end of Openstack EX210 official training book are good test for your skills. If you can do those exercises successfully without taking any help, you will be easily able to clear the exam.
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AWS VS AZURE VS OPENSTACK

Most of the services provided by different cloud providers are same as what you do in on-premises setup, they just have a different name in cloud. Below is comparison of major services offered by different cloud providers and what they mean in simple laymen terms. Hope this is helpful to you.