Active Memory Sharing (AMS)

When you enable the PowerVM™ Active Memory™ Sharing technology, you can configure multiple logical partitions to share the system's memory.



Logical partitions can share the memory in the shared memory pool by using the PowerVM Active Memory Sharing technology (or shared memory). Instead of assigning a dedicated amount of physical memory to each logical partition that uses shared memory (hereafter referred to as shared memory partitions), the hypervisor constantly provides the physical memory from the shared memory pool to the shared memory partitions as needed. The hypervisor provides portions of the shared memory pool that are not currently being used by shared memory partitions to other shared memory partitions that need to use the memory. When a shared memory partition needs more memory than the current amount of unused memory in the shared memory pool, the hypervisor stores a portion of the memory that belongs to the shared memory partition in auxiliary storage. Access to the auxiliary storage is provided by a Virtual I/O Server logical partition. When the operating system attempts to access data that is located in the auxiliary storage, the hypervisor directs a Virtual I/O Server to retrieve the data from the auxiliary storage and write it to the shared memory pool so that the operating system can access the data. The PowerVM Active Memory Sharing technology is available with the PowerVM Enterprise Edition hardware feature, which also includes the license for the Virtual I/O Server software.



For more information on Active Memory Sharing, see the following:





 

Document Type	Link	Comments
Redbook	AMS Redbook	90 pages, covers all Operating Systems
IBM Info Center Website	Overview of shared memory	Good Introduction
Whitepaper	IBM PowerVM Active Memory Sharing: An Overview	Covering the AIX Linux on Power and IBM i operating Systems by Erwin Earley, 10 pages
Official Online Movie	PowerVM Active Memory Sharing	On IBM TV, 6 minutes long
Hands-On Movie	AIX Wiki Movies	AIX Wiki, four movies a) Compared to Regular Paging, b) AMS Concepts, c) AMS Setup and d) AMS Simple Monitoring
Whitepaper	IBM PowerVM Active Memory Sharing Performance	Paper by Mala Anand (Power System Performance) including monitoring tools for IBM i, AIX and Linux on Power, 45 pages
Linux Wiki Article	AMS on Linux on Power	Lots of Linux specifics
LPAR2RRD documentation	LPAR2RRD AMS support	AMS freeware graphical monitoring