Tuesday, 24 April 2018

SCOM Agent performance counter showing dotted lines in graph

Many might have face this issue.

The only solution is to uninstall the SCOM agent ,reboot the server. Recreate the wmi repository, then install the SCOM Agne to resolve the issue.

Friday, 7 July 2017

Features of Apache Cassandra

* Elastic scalability - Cassandra is highly scalable; it allows to add more hardware to accommodate more customers and more data as per requirement.

* Always on architecture - Cassandra has no single point of failure and it is continuously available for business-critical applications that cannot afford a failure.

* Fast linear-scale performance - Cassandra is linearly scalable, i.e., it increases your throughput as you increase the number of nodes in the cluster. Therefore it maintains a quick response time.

* Flexible data storage - Cassandra accommodates all possible data formats including: structured, semi-structured, and unstructured. It can dynamically accommodate changes to your data structures according to your need.

* Easy data distribution - Cassandra provides the flexibility to distribute data where you need by replicating data across multiple data centers.

* Transaction support - Cassandra supports properties like Atomicity, Consistency, Isolation, and Durability (ACID).

* Fast writes - Cassandra was designed to run on cheap commodity hardware. It performs blazingly fast writes and can store hundreds of terabytes of data, without sacrificing the read efficiency.

Advantages of Apache Cassandra

* It is scalable, fault-tolerant, and consistent.

* It is a column-oriented database.

* Its distribution design is based on Amazon’s Dynamo and its data model on Google’s Bigtable.

* Created at Facebook, it differs sharply from relational database management systems.

* Cassandra implements a Dynamo-style replication model with no single point of failure, but adds a more powerful “column family” data model.

* Cassandra is being used by some of the biggest companies such as Facebook, Twitter, Cisco, Rackspace, ebay, Twitter, Netflix, and more.

What is Apache Cassandra

What is Apache Cassandra?

* Apache Cassandra is an open source, distributed and decentralized/distributed storage system (database), for managing very large amounts of structured data spread out across the world.

* It provides highly available service with no single point of failure.

What is mongo DB

MongoDB:

* MongoDB is a cross-platform document-oriented database system that avoids using the traditional table-based relational database structure in favor of JSON-like documents with dynamic schemas making the integration of data in certain types of applications easier and faster.

What is Apache HBase

Apache HBase :

* HBase is an open source, non-relational, distributed database modeled after Google’s BigTable and is written in Java.

* It is developed as a part of Apache Hadoop project and runs on top of HDFS, providing BigTable-like capabilities for Hadoop.

Differences between NoSql and relationship database

NoSQL vs. Relational Database

The following table lists the points that differentiate a relational database from a NoSQL database.

Relational Database:

1. Relational Database DatabaseSupports powerful query language.

2. It has a fixed schema.

3. Follows ACID (Atomicity, Consistency, Isolation, and Durability).

4. Supports transactions.

NoSql:

1. Supports very simple query language.

2. No fixed schema.

3. It is only “eventually consistent”.

4. Does not support transactions.