Java Heap Space vs Stack – Memory Allocation in Java

The difference between Java Heap Space and Stack is explained well in the link

http://www.journaldev.com/4098/java-heap-space-vs-stack-memory

Why to set -Xms and -Xmx to the same value?

This query is answered well in

https://developer.jboss.org/thread/149559?_sscc=t

In a production environment, if you monitor the GC data, you will notice that is a relatively short period of time (usually less than an hour), the JVM will eventually increase the heap size to the -Xmx setting. Each time the JVM increases the heap size it must ask the OS for additional memory, which takes time (and thus adds to the response time of any requests that were is process when the GC hit). And usually the JVM will never let go of that memory. Therefore, since the JVM will eventually grab the -Xmx memory, you might as well set it to that at the beginning.

Another point is that with a smaller heap size (starting with -Xms), GCs will happen more often. So by starting with a larger heap initially the GCs will happen not as often.

Finally, in a production environment, you usually run only one app server per OS (or per VM). So since the app server is not competing for memory with other apps you might as well give it the memory up front.

Multiple python versions using pyenv

https://realpython.com/blog/python/python-virtual-environments-a-primer/

Splunk Indexing and data retention

http://www.learnsplunk.com/splunk-indexer-configuration.html
https://splunk-sizing.appspot.com

Capacity Planning:
http://docs.splunk.com/Documentation/Splunk/4.3.1/Installation/CapacityplanningforalargerSplunkdeployment

Install Scala in Mac OS or Linux

1) Download scala-X.XX.tgz from the official site

2) Unzip archive
       tar xzvf scala-X.XX.tgz

3) mkdir /usr/local/scala/

4) cp -R scala-X.XX/* /usr/local/scala/.

5)  vi  ~/.bash_profile

6) Add scala/bin folder to your PATH
        export PATH=/usr/local/scala/bin:$PATH

Verify the Installation

$ scala
cat: /release: No such file or directory
Welcome to Scala 2.12.1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_101).
Type in expressions for evaluation. Or try :help.

scala>

PCI DSS - account data, cardholder data, SAD(Sensitive Authentication Data)

We normally think that account data and cardholder data are the same. But it is not so.
    - Cardholder data is a subset of account data

    - Account Data = Cardholder data + SAD
           - Account data includes all of the information printed on the physical card as well as data on the magnetic stripe or chip

   - Cardholder data
      - Primary Account Number(PAN)
      - Cardholder Name
      - Expiration Data
      - Service code

  - SAD
       - Full Track Data(magnetic stripe data or equivalent on a chip)
       - CAV2, CVC2, CVV2, CID
       - PINs/PIN blocks

PCI DSS Goals and Requirements

PCI DSS - has 6 goals. PCI DSS has 12 requirements to meet those 6 goals

Goal 1: Build and Maintain secure network and systems
        Req 1: Install and maintain a firewall configuration to protect cardholder data
        Req 2: Do not use vendor supplies defaults for system passwords and other security Parameters

Goal 2: Protect cardholder data
        Req 3: Protect stored cardholder data
        Req 4: Encrypt transmission of cardholder data across open, public Network

Goal 3: Maintain a Vulnerability Management Programme
        Req 5: Protect all systems against malware and regularly update anti-virus software or programs
        Req 6: Develop and maintain secure systems and applications

Goal 4: Implement Strong Access Control Measures
        Req 7: Restrict access to cardholder data by business need-to-know
        Req 8: Identify and authenticate access to system components
        Req 9: Restrict physical access to cardholder data

Goal 5: Regularly Monitor and Test Networks
        Req 10: Track and monitor all access to network resources and cardholder data
        Req 11: Regularly test security systems and processes

Goal 6: Maintain an Information Security Policy
        Req 12 : Maintain a policy that addresses Information Security for all personnel