Reducing the time to restart your system

Unfortunately, systems periodically experience an unplanned outage. Use the availability tools described here to restart your system as quickly as possible after an unplanned outage.

Before your system turns off, it performs certain activities to ensure that your data is protected and that jobs are ended in a controlled manner. When you experience an unplanned outage, your system cannot perform these activities. Each of these tools should be used together to quicken the startup times for your system.

For more details on what happens when your system ends abnormally, see Starting and stopping the system.

Use the Reducing iSeries IPL Time experience report to learn how to control the time that it takes to start your system.

System-managed access-path protection (SMAPP)

An access path is the route that an application takes through a database file to get to the records it needs. A file can have multiple access paths, if different programs need to see the records in different sequences. When your system ends abnormally, such as during an unplanned outage, the system must rebuild the access paths the next time it starts, which might take a long time. When you use system-managed access-path protection, the system protects the access paths so that they do not need to be rebuilt when your system starts after an unplanned outage. This saves you time when you restart your system, which enables you to get back to your normal business processes as quickly as possible.

Journaling access paths

Like SMAPP, journaling access paths can help you to ensure that critical files and access paths are available as soon as possible after you restart your system. However, when you use SMAPP, the system decides which access paths to protect. Therefore, if the system does not protect an access path that you consider critical, you might be delayed in getting your business running again. When you journal the access paths, you decide which paths to journal.

SMAPP and journaling access paths can be used separately. However, if you use these tools together, you can maximize their effectiveness for reducing startup time by ensuring that all access paths that are critical to your business operations are protected.

Protecting your access paths is also important if you plan to use a high availability product, such as IBM® PowerHA® SystemMirror® for i, to avoid rebuilding access paths when you failover to a backup system.

Independent disk pools

When a system is started or restarted, you can start each independent disk pools individually. By starting each independent disk pool separately, the system can be made available more quickly. You can prioritize the workload so that the critical data becomes available first. You can then vary on independent disk pools in a specific order based on this priority.