https://robmcnelly.com/10-things-to-love-about-aix/

Key Release Dates and End of Support

Ignoring AIX release 1 and AIX release 2, which were for early UNIX hardware from IBM called IBM RT and IBM PS/2.

AIX 3 (1990) for Power based processor computers (initially RS/6000) based on UNIX AT&T System V.2 and V.3 with some added BSD 4.2 features plus IBM unique features in simplifying systems management:

  Systems Management menu interface: smit & smitty
  Network Installation Management (NIM)
  Journaling File System (JFS)
  Logical Volume Management (LVM)
  Make a bootable system backup (mksysb)
  High Availability Clusters (HACMP) - later called PowerHA
  Real-time computing infrastructure

  AIX binary compatibility with AIX 3
  Symmetrical Multi-Processor (SMP) - A VERY BIG KERNEL CHANGE
  SMP hardware J30/R40 with 6 or 8 CPUs
  NIM Enhancements
  JFS greater than 2 GB 
  NFS v3
  32-bit/64-bit applications at the same time
  Add 16 GB total memory support
  Alternate disk installation AIX upgrade
  Last release 4.3.3

  AIX binary compatibility with AIX 4
  HMC and Hypervisor
  Virtualization of CPU & RAM
  Virtual disks + network = VIOS 
  Live Partition Mobility (evaluation)
  Dynamic LPAR: CPU + memory
  Symmetric multithreading SMT
  AIX MPIO 
  Concurrent I/O for RDBMS
  NPIV SAN virtualization
  Workload Manager (process groups)
  JFS2 – extent-based space allocation
  First Failure Data Capture (FFDC)
  PowerSC
  NFS version 4
  Last release 5.3
   

  AIX binary compatibility with AIX 5
  Live Partition Mobility (LPM) for production
  Workload Partition & Live Application Mobility (LAM)
  Versioned WPAR for AIX 5.2 & 5.3
  Role Based Access Control (RBAC)
  Encrypted JFS
  Trusted AIX
  AIXpert - system hardening by rules
  Kernel - Storage Keys for RAS
  Dynamic process tracing: ProbeVue
  Firmware assisted dump
  AES encryption for NFS v3 and v4
  Nigel’s performance monitor: nmon 
  Last Release 6.1 TL9
   

  AIX binary compatibility with AIX 6
  JFS2 Integrated Snapshots
  WPAR storage devices
  Role Based Access Control (RBAC)
  Encrypting JFS file system
  Trusted AIX and Trusted Execution
  Cluster Aware AIX (CAA)
  Snapshot of a JFS2 file system
  topas Multi-server
  JFS to JFS2
  Secure Shell (SSH) in base AIX
  Active Memory Expansion
  Transactional Memory
  Shared Storage Pool support
  PowerVC Support
  Last release 7.1 TL5 - functionally stabilized since AIX 7.2 arrived. Mostly bug and security fixes ever since.
   

  AIX binary compatibility with AIX 7.1
  Live (Kernel) Update capability for Technology Levels, Service Packs, and Fixes.
  Active Memory Expansion 64k page
  LVM thin storage block reclamation
  AIX Open Source Toolbox Enhancements
  SMB 2.1 client and SMB 3.0.2 client
  Migration to Cloud ready - create_ova
  Flash Cache For Fibre Channel disks
  Includes Dynamic System Optimizer (DSO)
  External Interrupt Virtualization Engine (XIVE)
  Live Kernel Update LKU Enhancements (2015)
  POWER9 HW NX GZIP engine
  Ansible "Paybooks" released for AIX
  Scaling enhancements – larger LPARs
  Simplified Remote Restart Supported
  Application address space randomization
  LVM passive mirror enhancements for concurrent I/O applications
  NIM HTTP support for updates
  Shared memory communications over RDMA (SMCR)
  AIX installation from USB flash drive (also added to AIX 7.1 TL5)
  Enhanced multi-queue NPIV performance
  Fibre Channel: Congestion Notification, 32 Gb support, and NVMe over Fibre Channel
  14 million open files per SRAD
  NVMe drive space reclaim
  GLVM HW assisted compression
  OpenSSH with Power HW GZIP compression

  AIX binary compatibility with AIX 7.2
  Power10 server support:
      Power10 support 240 cores & 1920 hardware threads per LPAR
      Matrix Maths Accelerator (MMA)
      OpenBLAS with MMA support, available from the AIX Toolbox 
      Optimized memcpy instructions
      For new generation IBM OpenXL compilers 
  Stronger default password rules and new default password algorithm (SSHA-256)
  telnet & ftp not in default installation (due to security risks)
  ”Out of the box” ready for POWER or Power10 hardware NX GZIP with "pigz" and create_ova supported
  New JFS2 file systems default to inline log
  Added Open Source bash 5.1 and Python 3.9
  AIX Open Source Toolbox that uses “dnf” & toolbox updated plus many extra packages
  Fast Dynamic LPAR resize CPU and memory
  Reduced LPAR boot times with large memory
  LVM Encryption for rootvg 
  128 TB JFS2 file system and file size
  Oracle 19c support
  Virtual Persistent Memory (vPMem) can be configured as a hdisk
  Live update of AIX kernel tunables (no, vmo)
  New IPsec features (NAT-T, IKE fragmentation)
  Stronger default security for AIX trace channel 0
  Sendmail support for SASL authentication
  TCP Cubic support
  Increased fork and exec scaling
  Enhanced Async IO IOPs scaling