IBM AIX 001 - Overview & Introduction

AIX Overview

AIX (stands for Advanced Interactive Executive) is IBM's proprietary operating system which is based on UNIX.  AIX developed by IBM is initially released on 1986. AIX runs on IBM's proprietary hardware called IBM Power Systems. As of 2019, there were 8 generations of POWER systems released.

The specialty about AIX and IBM Power system is, many instances of AIX (also known as LPARs) can be run on the same physical system. This is managed by the power system firmware called "Power Hypervisor".

What is an LPAR ?

LPAR is stands for Logical PARtition. As the name suggests, LPAR is a logically created separate system which runs on same physical fingerprint by sharing its processor, memory. I/O devices etc. 

So how the physical resources been shared between set of LPARs ? 

Power systems contains a firmware called "Power Hypervisor" which provides configuration capabilities for resource allocation and isolation. 

The interesting part of the LPAR is, it can be configured either to have dedicated physical devices for shared virtual devices. 

  

Once an LAPR has been created and configured, it can be treated as a separate environment with seperate IP, Date & Time etc.

What is DLPAR ? 

D in DLPAR is stands for Dynamic. Dynamic Logical Partitioning(DLPAR) means you can add, remove, move the resources without restarting the partition. As an example, imagine you are running an application on an LPAR and your user base got increased. Due to high number of users, memory consumption of the application is high and you need to extend the memory. This can be done using DLPAR concept without a down time. 

WPAR (Workload Partitioning)

WPAR is a virtualized, operating environment which is created with in an single AIX instance. This is somewhat similar to a docker running on a host. WPAR can be considered as the docker and LAPR is the host. WPAR is solely independent on hardware resources.  

Lets take a look at the above diagram. Click on it to view it on full size. This diagram shows a typical power server setup.  So what can be identified from this diagram.

• The server is provisioned with several LPARs
• The service processor of the server is marked on the diagram as well. Service processor is a special microprocessor within power server which is connected to Hardware Management Console(HMC) via RJ45 port. This service processor can be connected to maximum 2 HMCs. One for Live and One for Backup is the recommended way.
• There are 2 HMCs connected to the server via both private and public networks. One is used as primary HMC where admins login and do all the configurations on the server. It is recommended to have a backup/secondary HMC connected in case of failure of the first one.  
• A NIM (Network Installation Manager) server has been configured in order to help AIX installations. NIM holds AIX images use to provision LPARs.

HMC (Hardware Management Console)

HMC is where the system administrator do all the LAPR configuration work. HMC is connected to service processors of the power system. All the LPARs configured on the server and HCM is connected via a private/public network to the power system.   

Checkout next post on AIX HMC here.