OpenStack vs AWS

Today, I was having a discussion with a friend about OpenStack vs AWS ( public cloud) and our discussions  shifted  towards CAPex (capital expenses) vs  OPex (operational expenses).  He  mentioned that some companies like utility companies would like to have capex than opex so that they can charge the customers for the expenses. I am not sure about it and may be valid.

I strongly believe AWS seems to be the best platform if you are starting out new and would like to check the feasibility of an idea turning into a reality ( Infrastructure and Platform is taken care by the platform).  Also, security is as robust as possible in the public clouds through IPSec VPN Connections, Single sign on through federated services (ADFS), VPC and firewalls ( security groups and access control lists (ACL) at subnet levels.

So, when to use open stack?  Here are some of the reasons.

• When we have high performance computing applications  which requires high bandwidth and less latency.
• When we would like to customize our IAAS and PAAS platforms for better perfomance  of native applications
•  For supporting devops model. provide development, staging and production environments for developers.

All the scenarios specified above for OpenStack can also be efficiently designed using the public cloud infrastructure. But may come at a higher expense. Bottom line is the  cost efficiency and resource efficiency. Also, as stated above, which expenses make more sense for a company. 

I truly believe public cloud is here to stay and we may see more of hybrid clouds  where companies implementing private clouds may end up using certain services of public clouds  like durable and reliable storage services ( S3, Glacier , storage gateway) as needed. 

Here is an interesting Gartner article  discussing this issue. 

Here is a link that compares OpenStack and AWS components/services and costs

Redis Caching and AWS

I was reading today about ElastiCache AWS service that currently supports MemCache and Redis implementations

MemCache  is the key Value based caching that is multi threaded and supports the thread or parallel performance based on the cores. Horizontal scaling can be easily done with MemCaching

Redis is a different kind of caching which has lot of in built features that can be programmed through APIs provided. Redis supports Asynchronous replication, has built in persistence and  supports both key value as well as data structures such as sets, lists and hashes. Redis  supports point in time snapshots at regular intervals and also write through persistence ( persist whenever there is a write or update). For more information about Redis persistance, click here

Since Redis data structures cannot be sharded across different instances, we cannot scale horizontally in a cluster  like memcache.  However, we can have multiple clusters with each cluster having a single instance. Architecture for Redis looks very similar to AWS RDS ( Relational Database Service)

The question, I have is , can Redis with inbuilt persistence, be used as Database? It can be if the data model can be fit into the memory . Downside to this approach is that the memory is expensive.  Also, what happens if there is a crash?  As stated above,  Redis can do regular and write through backups as per our RPO and RTO guidelines.

It is nice to see some one addressing the same issue here. 

can Redis be used as super fast memory database

AWS Solution Architect

I am currently preparing for AWS solution architect and planning to take associate and professional exam in January.

How am I preparing?

AWS website is amazing in terms of documentation.
Had glanced through amazon documentation for all the services provided by Amazon
Had taken a sample test paying 20$ to know where I stand at
https://www.webassessor.com/wa.do?page=publicHome&branding=AMAZON.  Not bad at all.
White papers published by AWS are a great source of information for cloud architectures and provides great insight. Also doing my hands on experience at qwiklabs


The good part about these exams is that they focus more on the scenarios and not on some quantitative data ( like how much memory per instance type). The critical part is the time management for these exams. Have to be really quick in going through these scenarios and picking up the choices.

Will update this post as I come across more information about these exams (tips, preparation material, questions etc)

What am I reading now?

Last time, when I had been to India, stumbled across a book written by vivekananda. The title of the book is " THE COMPLETE BOOK OF YOGA"



very interested facets about dealing with life. have finished the Karma yoga  part but would like to revisit again