Enhancing availability with the AIX software
PowerHA® SystemMirror® takes advantage of the features in AIX® - the high-performance UNIX™ operating system. AIX adds new functionality to further improve security and system availability.
This includes improved availability of mirrored data and enhancements to Workload Manager that help solve problems of mixed workloads by dynamically providing resource availability to critical applications. PowerHA SystemMirror provides both horizontal and vertical scalability without downtime for your system. The AIX operating system provides numerous features designed to increase system availability by lessening the impact of both planned (data backup, system administration), unplanned (hardware or software failure) downtime, and flexibility in hardware resource management by using Capacity on Demand (CoD) functions.
The AIX operating system provides the following features:
- Journaled File System and Enhanced Journaled File System
- Disk mirroring
- Process control
- DLPAR and CoD
- Workload Partitions
Journaled file system and enhanced journaled file system
The AIX native file system, the Journaled File System (JFS), uses database journaling techniques to maintain its structural integrity. System or software failures do not leave the file system in an unmanageable condition. When rebuilding the file system after a major failure, AIX uses the JFS log to restore the file system to its last consistent state. Journaling thus provides faster recovery than the standard UNIX file system consistency check (fsck) utility. In addition, the Enhanced Journaled File System (JFS2) is available in AIX.
Disk mirroring
Disk mirroring software provides data integrity and online backup capability. It prevents data loss due to disk failure by maintaining up to three copies of data on separate disks so that data is still accessible after any single disk fails. Disk mirroring is transparent to the application. No application modification is necessary because mirrored and conventional disks appear the same to the application.
Process control
The AIX System Resource Controller (SRC) monitors and controls key processes. The SRC can detect when a process terminates abnormally, log the termination, pass messages to a notification program, and restart the process on a backup processor.
Dynamic LPAR management
- Capacity on Demand (CoD) functions (including On/Off CoD and Enterprise Pool CoD) manage memory and CPU resources at the frame (CEC) level.
- DLPAR functions manage memory and CPU resources at the logical partition level.
With the ROHA function, you can use PowerHA SystemMirror to optimize the amount of resources for each application. For example, during a takeover the hardware resources (CPU and memory) are dynamically released from the active node, and dynamically acquired and allocated to the standby node.
Workload Partitions
Workload Partitions allow multiple instances of an application to run within the same operating system environment while providing isolation between those environments, thus providing protection and isolation between instances.
Cluster Aware AIX (CAA)
PowerHA SystemMirror uses the AIX clustering capabilities to provide for an advanced high availability solution. CAA provides the AIX kernel with heartbeating and health management. PowerHA SystemMirror monitors for fine granular storage and network events and handles the critical situations in the AIX operating system. PowerHA SystemMirror can discover hardware components, thus making it easier to manage and deploy clusters.