Friday, May 22, 2015

A client error (AuthFailure) occurred: AWS was not able to validate the provided access credentials


Amazon Web Services (AWS) offers both the web-based management console as well a command line interface (CLI). The other day we were use the CLI on an EC2 instance running Red Hat Enterprise Linux Server release 6.4 operating system. But even after installing and configuring the CLI using the AWS CLI user guide, every CLI command was failing with the "A client error (AuthFailure) occurred..." error. For example, the basic command "aws ec2 describe-instances --region us-west-2" failed with the below error.

A client error (AuthFailure) occurred when calling the DescribeInstances operation: AWS was not able to validate the provided access credentials.


The date command returned an incorrect time. Whereas the actual time is Fri May 22 23:33:18 EDT 2015, it returned Sat May 23 03:33:18 EDT 2015.  We then found that the NTP daemon was not running (Network Time Protocol). Once we started the ntpd deamon, the "aws ec2 describe-instances --region us-west-2" worked and returned the expected output in the AWS CLI default JSON format. We followed the AWS user guide on how to start the ntpd deamon successfully.

1. ntpstat
Unable to talk to NTP daemon. Is it running?

2. sudo service ntpd start
Starting ntpd:                                             [  OK  ]

3. sudo chkconfig ntpd on

4. ntpstat
   polling server every 64 s

5. date

The date command then returned the correct time.

6. aws ec2 describe-instances --region us-west-2

Finally, the aws ec2 command above returned the output successfully.

Saturday, May 2, 2015

How to install and setup Oracle 12c RAC on PC using VirtualBox


Are you spending many hours in figuring out how to install and setup Oracle 12c RAC cluster on your PC ? DBA University will help you perform a successful installation and setup of Oracle 12c on your PC using Oracle VirtualBox hypervisor if you register for our comprehensive training course in Oracle 12c ASM, RAC and Data Guard topics.  

This course is conducted by Michelle Malcher. Michelle is a well experienced Oracle Database Administrator. She is a well known author of several Oracle Press books. Also, she is an Oracle ACE Director (only a few in the world are recognized as ACE Director by Oracle Corporation) and a noted contributor to Oracle Magazine.

Course Timings

2) Evenings - Sun, Mon, Tue and Thu  - 7 pm Central Time to 9 pm Central Time.
3) Online Training, but very interactive with whiteboard teaching methodology.

Course Details and Lab Work

1) We will provide you the VM that will help in a hassle-free and successful 2 Node RAC cluster on Linux operating systems using Oracle VirtualBox.  We have taken care of all the details and in just a week, you will have a working 2 Node RAC cluster on your PC. 

2) We will provide detailed training material (eBook) that will list all the hardware and software pre-requisites, network setup tasks and screenshots for a successful Oracle 12c Grid Infrastructure and Oracle 12c RDBMS software installation on the 2 Node cluster.

3) We also have separate lab exercises on Oracle 12c ASM (Automatic Storage Management) that includes how to partition and configure disks for ASM usage using the Linux ASMLib utility, ASM mirroring and how to replace failed disks in an ASM disk group. 

4) You will also become very strong in learning how to setup and maintain an Oracle 12c Data Guard environment.

Course Brochure and Registration

1) Click here to see the course topics.
4) Fee is $799 and paid online using the above registration link.
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