Thursday, 21 September 2017

Ignoring Files ( Git Environment )


If you create a file in your repository named .gitignore, Git uses it to determine which files and directories to ignore, before you make a commit.
.gitignore file should be committed into your repository, in order to share the ignore rules with any other users that clone the repository.

Explicit Repository Excluded

If you don't want to create a .gitignore file to share with others, you can create rules that are not committed with the repository. You can use this technique for locally-generated files that you don't expect other users to generate, such as files created by your editor.
Use your favorite text editor to open the file called .git/info/exclude within the root of your Git repository. Any rule you add here will not be checked in, and will only ignore files for your local repository


Sunday, 10 September 2017

Web Application Tools

Some tools that can aid you in developing a personal or even business web page.

For design : use

For responsive testing :

Coding Reference

1. Bootstrap ( W3Schools )

Intro -
Customize -

Section Scroll (Aminate)

Smooth Scroll-to-Top (Animate)

How to apply CSS Animation

2. CSS ( CodeAcademy )

3. JavaScript Development

JavaScript Intro

Explanation about Waypont + Animate css

4. Web Developer Bootcamp ( Udemy )

5. Foundation of Front End ( Udemy )

Optimal User Experience Topic

Friday, 8 September 2017

Physical and Virtual RDMs Compatibility

An RDM is a special mapping file in a VMFS volume that manages metadata for its mapped device. The mapping file is presented to the management software as an ordinary disk file, available for the usual file-system operations. To the virtual machine, the storage virtualization layer presents the mapped device as a virtual SCSI device.

 RDM has two compatibility modes:

  • Physical compatibility mode 
  • Virtual compatibility mode

Physical Compatibility Mode
  • Physical mode specifies minimal SCSI virtualization of the mapped device, allowing the greatest flexibility for SAN management software. 
  • The VMkernel passes all SCSI commands to the device, with one exception - The REPORT LUNs command is virtualized, so that the VMkernel can isolate the LUN to the owning virtual machine. Otherwise, all physical characteristics of the underlying hardware are exposed. 
    •  Note: Other VMkernel modules have the ability to intercept I/O to perform relevant operations such as NMP, Drivers, etc. For a graphical representation of the ESXi storage stack, see the VMkernel and Storage section of the vSphere Storage Guide for ESXi 5.0, ESXi 5.5 and ESXi 6.0. 
  • Physical mode is useful while running SAN management agents or other SCSI target-based software in the virtual machine. 
  • Physical mode also allows virtual-to-physical clustering for cost-effective high availability. 
  • Virtual Machine Snapshots are not available when the RDM is used in physical compatibility mode. 
  • You can use this mode for Physical-to-virtual clustering and cluster-across-boxes. 
  • VMFS5 supports greater than 2 TB disk size for RDMs in physical compatibility mode only. These restrictions apply: 
    •  You cannot relocate larger than 2 TB RDMs to datastores other than VMFS5. 
    • You cannot convert larger than 2 TB RDMs to virtual disks, or perform other operations that involve RDM to virtual disk conversion. Such operations include cloning.

Physical Compatibility Mode

  • Virtual mode specifies full virtualization of the mapped device. 
  • VMkernel sends only READ and WRITE to the mapped device. The mapped device appears to the guest operating system exactly the same as a virtual disk file in a VMFS volume.
  • The real hardware characteristics are hidden. 
  • If you are using a raw disk in virtual mode, you can realize the benefits of VMFS, such as advanced file locking for data protection and snapshots for streamlining development processes. 
  • Virtual mode is more portable across storage hardware than physical mode, presenting the same behavior as a virtual disk file. 
  • You can use this mode for both Cluster-in-a-box and cluster-across-boxes.


Virtual Machine File System (VMFS)

VMFS is one of the critical component of VMware vSphere storage stack as it abstracts the underlying storage and presents it to Virtual Machine in various formats; virtual disk, passthru RDM, Non-Passthrough RDMs, Snapshots and so on. VMware widely used features like High Availability(HA), vMotion, Storage vMotion, Disributed Resource Scheduler (DRS) build up on this File System.

Raw device mapping (RDM) is an option in the VMware server virtualizationenvironment that enables a storage logical unit number (LUN) to be directly connected to a virtual machine (VM) from the storage area network (SAN).

In this blog, we are going to discuss about Basics of VMFS file system, its features and benefits. Why VMFS is called Clustered file system and how its different from conventional file systems.

So What is VMFS ?

VMware Virtual Machine File System is a high performance cluster file system which provides storage virtualization optimized for virtual machines. While conventional file systems allow only one server at a time to have read-write access to the same file system. VMFS leverages shared storage to allow multiple VMware vSphere hosts to read and write to the same storage concurrently.

Figure 1.0 Multiple ESX accessing VMFS

Above figure shows how multiple ESX servers with several virtual machines running on them can use VMFS to share a common clustered pool of storage. VMFS clustering feature provides the foundation for enabling services such as vMotion, Storage vMotion, High Availability(HA) and Distributed Resource Schedule (DRS).

Feature of VMFS

  • Encapsulation of the entire virtual machine state in a single directory.
  • Optimization for virtual machines in a clustered environment.
  • Dynamic datastore expansion by spanning multiple storage extents.
  • Lock management and distributed logical volume management
  • Clustered file system with journal logging for fast recovery.

Benefits of VMFS

As an automated storage interface for Virtual Machines environment. VMFS provides both an automated cluster file system capability and intelligent cluster volume management functions. VMFS has a number of benefits that make it particularly well suited as a cluster file system for the virtual environment.

  • Simplify virtual machine provisioning and administration by storing the entire virtual machine state in central location
  • VMFS stores all the files that makes up the virtual machine in a single directory or encapsulate entire VM state in a single director.
  • It simplifies provisioning and Administration of VMS
  • VMFS provides distributed infrastructure services for multiple ESX servers like HA, DRS, vMotion etc.
  • VMFS enable dynamic growth of datastores by adding multiple extents to it on fly.
  • VMFS creates point in time copy of virtual machine data that can be used for testing, backup and recovery operations.
  • VMFS is journaling filesystem which recovers virtual machine faster and more reliably in event of server failure with distributed journaling.
  • VMFS uses on-disck locking mechanism to make sure a single virtual machine is not powered up on multiple vsphere hosts at a same time.
  • It also simplifies disaster recovery using cloning, templates, migration technology.

VMFS Architecture

VMFS holds files and has its own metadata. Metadata gets updated through

  • Creating a file
  • Changing a file's attributes
  • Powering on a VM
  • Powering off a VM
  • Growing a file
When Metadata is updated, the Vmkernel places a non-persistent Small Computer System Interface (SCSI)
Reservation on the entire of VMFS volume.

  • lock held on volume for the duration of operation
  • Other Vmkernel are prevented from doing metadata updates

Thursday, 7 September 2017

Related Cloud Storage & Server Document

vCloud Director Installation


VMware Product Documents


VMware Product Guide


Rules and Rule Set (above vSphere)


Explanation VMware ESXI


VMware Storage / vSphere Documentation

VMware hands-on-lab

Modernizing the Data Center


Software Defined Storage


Introduction to the Software-Defined Data Center


Disable Typing Animation on Word 2016

If you only want to disable animation in Office 2016, open Word and Excel and

- select 'File'
- select 'Options'
- select 'Advanced'
- towards the bottom, in the section 'General', untick 'Provide feedback with animation'

Wednesday, 6 September 2017

Configuring Oracle databases for vCloud Director

Open command prompt on the window system to use oracle SLI.

1. Set Oracle System ID,

C:\Users\Administrator> set ORACLE_SID=orcl

2. To login system as database admin,

C:\Users\Administrator> sqlplus "/as sysdba"

3. When you create the Cloud Director database user account, you must specify CLOUD_DATA as the default tablespace,

Create user $vclouduser identified by $vcloudpass default tablespace CLOUD_DATA;

4. To grant privileges for vCloud user,


5. The database must be configured to use the AL16UTF16 character set. To check the National Character Set, run the command:

SQL> select * from nls_database_parameters where parameter = 'NLS_NCHAR_CHARACTERSET';

6. To check the number of configured sessions, run the command:

SQL> show parameter sessions;


VMWare vCloud Director

VCloud Director (vCD) is VMware Inc.’s cloud computing management tool. It manages Infrastructure as a Service (IaaS) architecture by monitoring and controlling various cloud-computing components, such as security, virtual machine(VM) provisioning, billing and self-service access. It focuses on private and hybrid cloud-computing infrastructres
How does vCloud Director Support Cloud Providers ?

Easy Cloud Consumption
HTML 5 UI provides for simplified workflows and the fastest, easiest path to service monetization and revenue realization.

Seamless Data Center Extension
vCloud Director enables simple, secure VM migration and data center extension. It allows for tenant-driven workflows, seamless connectivity, cold and warm migration options, and on-premises and cloud-view visibility and monitoring.

Certified Reference Design for VMware Cloud Providers
The VMware Cloud Provider Platform helps providers achieve operation efficiency by rapidly enabling and monetizing highly scalable cloud environment using vCloud Director and the SDDC stack.

Delivers Multi-Tenancy Platform
You can reduce operational costs by using a single platform to host secure virtual data centers that could be consumed by multiple tenants using Role-Based Access Control.


Tuesday, 5 September 2017

Directory Traversal Attack

Directory Traversal is an HTTP exploit which allow attackers to access restricted directories and execute commands outside of web server’s root directory.

2 main levels of security mechanisms:
·        Access Control Lists (ACLs)
·        Root directory

An access control list (ACL) is used in the authorization process. It is a list which the web server’s administrator uses to indicate which users or groups are able to access, modify or execute particular files on the servers, as well as other access right.

Sample picture of wampserver folder ;

The root directory is a specific directory on the server file system in which the users are confined. Users are not able to access anything above root folder. For example, the default root directory of wampserver on windows is located at C:\Wamp64\www and with this setup, a user does not have access above folder such as C:\Windows but have access under the root directory (provided that the user is authenthicated via the ACL).


Tetraphobia can be define as avoidance in instance of number 4.

In mandarin (chinese) language, number 4 is pronounced as sì, however it also similar to sound/pronounciation of death sǐ.

Same as japanese, the word shi (し, Japanese) which also similar to pronounce of death (shi-nigami).