IBM i series Handbook page 56

iSeries Architecture: Fundamental Strength of the iSeries
transmitted to the secondary system and applied when the backup is complete,
therefore, providing continuous protection.
• The secondary system can be used for other activities, for example, business
intelligence or application development, while it concurrently provides backup to the
primary system. The secondary system can also be used to "load balance", to offload
work of the primary system.
• Selection of which items on the primary system to dynamically protect by the
secondary system. This can minimize disk capacity on the secondary system or allow
a smaller model to be used to "cross-system mirror" the larger system.
• Cross-protection among two or more systems, hundreds of miles apart. Data integrity
is maintained in both directions. Backups can be performed at the remote site.
• New software versions and releases (OS/400 and associated software), or fixes on the
secondary system can be applied while the primary system continues to function.
Testing can occur on the secondary system before non-disruptively updating the
primary system.
iSeries servers offers superior technology, service, and support in each of five critical
components of availability:
• Single system reliability: Architecture and baseline design make the iSeries server one
of the most reliable servers in the world. The iSeries serves the small business customer
with minimal skill or resource to manage complex environments. From its inception, the
iSeries architecture inherits a design where reliability and availability are equal
parameters to features like processor speed, memory capability, and number of disk
arms.
iSeries design and development resources enable high levels of availability in a single
system environment. This highly reliable design is useful for unplanned outages by the
iSeries customer. The single-system iSeries remains the core building block to repeat and
extend functions into other areas of the business.
• Single-system availability management: iSeries servers have high-availability
facilities that are fast, automated, and easy to use. Best availability practices are
accessible to help reduce the duration of planned and unplanned outages. These high
availability practices include facilities such as:
– Save-while-active
– Parallel save and restore
– Backup Recovery and Media Services (BRMS) for iSeries
– RAID-5 disk parity protection
– Disk mirroring protection
– Automated journal management
– Access path protection
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iSeries Handbook