OpenBoot ok PromptMost of the time, you
operate a server at run level 2 or run level 3, which are
multiuser states with access to full system and network resources.
Occasionally, you might operate the system at run level 1, which is a
single-user administrative state. However, the lowest operational state
is run level 0. At this state, it is safe to turn off power to the
system.
When a server is at run level 0, the ok prompt appears. This prompt indicates that the OpenBoot firmware is in control of the system.
There are a number of scenarios under which OpenBoot firmware control can occur.
- By default, before the operating system is installed the system comes up under OpenBoot firmware control.
- When the auto-boot? OpenBoot configuration variable is set to false, the system boots to the ok prompt.
- When the operating system is halted, the system transitions to run level 0 in an orderly way.
- When the operating system crashes, the system reverts to OpenBoot firmware control.
- During the boot process,
when there is a serious hardware problem that prevents the operating
system from running, the system reverts to OpenBoot firmware control.
- When a serious hardware problem develops while the system is running, the operating system transitions smoothly to run level 0.
- When you deliberately place the system under firmware control in order to execute firmware-based commands.
It is the last of these
scenarios which most often concerns you as an administrator, since
there will be times when you need to reach the ok prompt. Several ways to do this are outlined in Reaching the ok Prompt. For detailed instructions, see Getting to the ok Prompt.
Reaching the ok Prompt
There are several ways to reach the ok
prompt, depending on the state of the system and the means by which you
are accessing the system console. In order of desirability, these are:
- Graceful shutdown
- ALOM system controller break and console command pair
- L1-A (Stop-A) keys or Break key
- Manual system reset
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