blog.meyawi.com

This my first post and I’m going to blog about WPAR technology 

Presentation

What is a WPAR ?  WPAR = Workload PARtition.
It is a software virtualization/partitioning system within an AIX instance which allows isolating execution environment, as share and resources control allocation (cpu, ram, network) in order to limit interactions between others WPAR, and AIX hosting operating system.

This technology had been introduced since AIX 6.1 release and there are several kinds of WPAR (application, system…).
We could establish an “analogy” of virtualization technologies between physical server LPAR on one hand, and AIX WPAR in the other hand, which could involve next configuration example :
Physical Server > LPAR > AIX > WPAR.

General Points

• Global Environnement :

Part of AIX instance hosting WPAR, which doesn’t belong ton any WPAR

• WPAR :

– Execution environment isolation = WPAR sees only its processes and resources
– IP attribution possibility
– Restricted IPC (Inter Process Communication)
– Resources allocation/control (cpu, mem…)

WPAR types

As said above, there are several WPAR types.

• Application WPAR :

– Application/command isolation (execution life time)
– No specific environment needed
– Creation in a few seconds
– Command : wparexec

• System WPAR :

– Similar to an AIX system
– Further isolation (process, users, filesystem)
– Shared filesystems with Global Environnement (shared WPAR) and/or dedicated filesystems (Detached/Private WPAR)
– Possibility of dedicated hdisk device usage (FC, vscsi, scsi) => Rootvg WPAR
– Creation in a few minutes
– Command : mkwpar

• Versioned WPAR :

– Ability to run AIX 5.2 (TL10SP8) or AIX 5.3 (TL12) as a WPAR (particular case of System WPAR)
– AIX 7.1 & POWER 7 only !!
– Mksysb restore of old system
– Consolidation
– Necessarily Detached WPAR

History

Backup / Restore

• Global environment Mksysb (–N option to include inactive WPAR)
• Specific command : savewpar
– Like mksysb command
– Exclude : /etc/exclude.WparName
• List files in a backup file : lssavewpar
• Restore : restwpar
• Definition and Backup from a NIM server
• Ability to clone WPAR (spec file)

Benefits

• Resource use optimisation (WLM)
• Fast Deployment/Provisionning
• Isolation et security
• Consolidation
• Administration/Exploitation simplification
• Disaster/Failure Recovery (checkpoint, Live Application Mobility, job)
• Extended AIX 5.2 et 5.3 support, included in AIX 7.1 support, for Versioned WPAR

Conclusion

In my opinion, WPAR could be a very interesting and useful technology in some cases. For example, where multiple small isolated environment provisioning is needed. It could also be helpful for testing purpose without risking system corruption.

The main asset is without a doubt the ability to run AIX 5.2 (indeed 5.3) in a WPAR hosted by an AIX 7.1, in order to benefit POWER7 cores computing power and AIX 7.1 software maintenance. As a reminder, AIX 5.2 is no more supported, and AIX 5.3 end of support is planned for April 2012, so in both cases extended support is needed with an additional cost which could be balanced with the cost of a new POWER7 server…

In a future post, I will make a deep dive in WPAR creation and use.