000-221 · Question #44
Users on a server are receiving errors stating that they cannot fork any additional processes. The administrator checks server paging space and finds that it is only 5% used. What is the next most…
The correct answer is D. The system has the default maxuproc system attribute. This should be increased to a value appropriate. When paging space is not the bottleneck, the most common cause of fork failures in AIX is the maxuproc system attribute, which imposes a hard cap on the number of processes any user can run concurrently.
Question
Users on a server are receiving errors stating that they cannot fork any additional processes. The administrator checks server paging space and finds that it is only 5% used. What is the next most likely cause of the forking issue and what action should be taken to resolve it?
Options
- ACorruption has occurred to the bos.rte.control fileset. Reinstall the fileset with the -f option.
- BThe number of fixed licenses has been reached. Use 'chlicense' to increase the limit and reboot the system.
- CSystem requires additional table space as well as paging space. Check the table space and increase
- DThe system has the default maxuproc system attribute. This should be increased to a value appropriate
How the community answered
(40 responses)- A18% (7)
- B8% (3)
- C5% (2)
- D70% (28)
Why each option
When paging space is not the bottleneck, the most common cause of fork failures in AIX is the maxuproc system attribute, which imposes a hard cap on the number of processes any user can run concurrently.
Corruption of bos.rte.control would produce broad system instability or missing core utilities, not a user-specific process-limit error.
AIX fixed licenses govern the number of concurrent user logins permitted, not the number of processes an already-logged-in user may fork.
Table space is a database-layer concept unrelated to OS process creation, and the question already eliminates paging space as the root cause.
The maxuproc attribute on the sys0 device in AIX sets the system-wide maximum number of concurrent processes per user. When workloads exceed the default value, the kernel returns EAGAIN on fork calls even though memory and paging space are available. The administrator should run 'chdev -l sys0 -a maxuproc=<new_value>' to raise the limit to a level appropriate for the environment, which typically takes effect without a full system reboot.
Concept tested: AIX maxuproc process limit tuning
Source: https://www.ibm.com/docs/en/aix/7.3?topic=o-overview-performance-tuning
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