Active Memory Deduplication

Active Memory™ Deduplication is a feature that is available on systems that have the PowerVM® Active Memory Sharing technology. PowerVM Active Memory Sharing is available with the PowerVM Enterprise Edition hardware feature. Active Memory Deduplication is a virtualization technology in which memory pages with identical contents are coalesced (or deduplicated) in physical memory. Active Memory Deduplication aggregates the same data in one memory position, and frees other duplicate memory blocks, thus optimizing memory use.

Under usual workloads, a system stores data in main memory and uses data from the main memory. The same data might be stored in multiple locations across the memory, especially data that contains code instructions. Additionally, operating systems used by multiple users have duplicate memory pages. Duplication of these memory pages is even more visible among virtualized systems on the same server where multiple operating system instances exist together in main memory. In this scenario, memory chunks for the same operating system or workload are loaded into memory by each logical partition. Resources do not operate optimally when identical data chunks are stored in multiple memory positions. To make system memory more efficient, Active Memory Deduplication avoids data duplication across separate memory positions.

We would like to thank the IBM® Redbooks® team for the generous use of their Power Systems™ Memory Deduplication Redpaper™ in developing this information.