Dynamic Logical Partitioning
| Company type | Technology feature |
|---|---|
| Industry | Information technology |
| Founder | IBM |
| Products | Logical partitioning, resource allocation |
Dynamic Logical Partitioning (DLPAR) refers to the ability of a logical partition (LPAR) to be modified on-the-fly without requiring a shutdown of the operating system running within that partition. This technology allows for the seamless reallocation of memory, CPU resources, and I/O components among LPARs on the same physical server without causing service interruptions.
Support for DLPAR has been available in AIX and IBM i across nearly all POWER4 and later POWER platforms. Initially, the Linux kernel on POWER systems enabled DLPAR functionality only for CPU resources and PCI devices, with memory reconfiguration excluded. However, as of October 2009, Linux extended its DLPAR capabilities to include memory management on POWER hardware. The core principles behind DLPAR are comprehensively discussed in the IBM Systems Journal article titled "Dynamic reconfiguration: Basic building blocks for autonomic computing on IBM pSeries Servers."
With the introduction of the POWER5 processor, DLPAR capabilities were significantly enhanced, featuring micro-partitioning, which supports up to 10 LPARs per processor and a total of 254 LPARs within a multiprocessor server environment. This architecture facilitates running as many as 254 separate operating system instances concurrently.
The primary application of DLPAR lies in creating flexible IT infrastructures and automating the distribution of hardware resources to improve overall system efficiency. It allows for the addition, removal, or reassignment of memory, CPUs, or I/O slots among LPARs without needing to reboot either the operating system or any running applications. For instance, IBM DB2 is capable of dynamically adjusting its performance parameters in response to changes triggered by DLPAR events.
On IBM Z mainframes and their associated operating systems—including Linux on IBM Z—more sophisticated dynamic partitioning features are supported, such as Intelligent Resource Director, Sysplex, and HiperSockets. The System z9 model can accommodate up to 60 LPARs per server and supports virtualization at scale with z/VM, enabling thousands of operating system instances to run simultaneously.