An enhancement made in 7.1 was the support of Suspend/Resume, a feature of PowerVM that was already supported on AIX and Linux.
From the RFA:
PowerVM includes support for an IBM i partition to be suspended, and later resumed. Using Suspend/Resume, clients can perform long-term suspension of partitions, which frees server resources used by that partition, and later resume operation of that partition and its applications on the same server.
Why might you be interested in suspending an i partition? There are numerous examples:
- Free up system resources for other partitions to use.
- Suspend workloads and applications so that hardware maintenance can be done, resuming the partitions later, thus starting up where they were running and avoiding a full IPL of each partition.
- Energy savings; use fewer processors when the workloads aren’t needed.
- Perhaps you have some long-running tests, but you’d like to save energy by not running those tests overnight; you could suspend the work and only run the tests during the day, without losing the work you’ve already done.
To use Suspend/Resume with i requires the following:
- IBM i 7.1 with Technology Refresh 2 PTF Group or any more recent IBM i release. (This post was originally written at the 7.1 timeframe, but this support is applicable to all current IBM i releases).
- The logical partition must be configured to use all virtual I/O (i.e., the virtual I/O server is required and you must be using external storage)
- The partition must be managed by an HMC
- The partition must be configured to allow it to be suspended through the HMC
- The resume of the partition must occur on the same system on which the suspend was done
- Control of suspending–and subsequently resuming–an IBM i partition is done through the HMC as an interactive procedure. The operating system will validate that it’s in a state that’s acceptable to suspend.
- A partition can remain suspended indefinitely. When you resume a partition, its saved state is restored and it will begin to function as it had prior to the suspend. There may be a burst of activity that occurs when a partition is resumed since it will appear to the system that the clock has been moved forward. Functions that are time-interval based may begin running immediately when the partition is resumed, while other functions will run when the next timer interval expires.
- The capability to suspend an IBM i partition is an exciting new enhancement.
This blog post was originally published on IBMSystemsMag.com and is reproduced here by permission of IBM Systems Media.