Micro-partitioning

It's been a while since I blogged. I find it as a great outlet and store for my thoughts and readings.

With the advent of virtualization, CPU /memory/storage/os can all be virtualized--imagined and it makes things little convoluted to comprehend. I have seen many experienced folks getting confused with these concepts.

Here's my attempt to clarify and

Whole processor partitions by definition contain no fractional processor allocations and thus contain an integer number of processor whereas, micro-partition provides flexible and efficient use of system hardware resources by allowing physical processors to be shared (time-sliced) between micro-partitions.


In micro-partitioning,each LPAR can operate in 3 different modes:

Guranteed/Dedicated

• LPARs are defined as dedicated or shared
• Dedicated partitions use whole number of CPUs

Shared partitions use whole and/or fractions of CPUs (smallest increment is 0.1, can be greater than 1.0)

• Borrowing/Using extra CPU cycles from the pool
• Donating/Donate CPU cycles to the pool

Shared processor pool - subset (or all) of the physical CPUs in a system
Physical processors shared among all of the SPLPARs within the shared processor pool

Entitled processing capacity expressed in 0.1 CPU increments

• Desired: Size of partition at boot time
• Minimum: Partition will start will less than desired, but won’t start if minimum capacity not available DLPAR changes to desired cannot be below the minimum.
• Maximum: DLPAR changes to desired cannot exceed this capacity

Uncapped:

• No Processing unit usage is limited to desired setting and cannot access extra cycles from the pool
• Yes Processing unit usage is allowed to exceed the desired processing unit setting but limited to a maximum of 1 for a Virtual processor

Use weighting to determine preference for spare cyclesAutomatic Load Balancing (default is 128, 0 implies no use of spare cycles, 255 is max Weight)




Virtualization is classified in different layers as

• Physical/dedicated
• Virtual/shared
• Logical (if SMT is turned on)

Useful links


http://www.ibmsystemsmag.com/aix/administrator/lpar/An-LPAR-Review/?page=1


http://regions.cmg.org/regions/stlcmg/files/Download/Presentations_2009-05/CMG%20Processor%20Virtualization.ppt


http://www.ibmsystemsmag.com/aix/administrator/systemsmanagement/Configuring-Processor-Resources-for-System-p5-Shar/?page=1

http://regions.cmg.org/regions/phcmg/Feb08PWeilnau.ppt