Tuning Asynchronous-I/O Kernel parameters to avoid error KAIO out of resource on HP-UX
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| Problem(Abstract) |
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This article goes over the Operating System Kernel that can be
configured to avoid error KAIO out of resource on the HP-UX platform |
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| Resolving the problem |
PROBLEM
When using Kernel Asynchronous I/O (KAIO) with IBM Informix Dynamic
Servers, you might experience the following message in the database
server message log:
KAIO out of resource errno=11
or
KAIO out of resource errno=35
CAUSE
This error indicates a shortage of KAIO resources.
SOLUTION
Tune the KAIO subsystem:
1. Configure the number of KAIO requests.
Note: Check Related information for more detail.
2. Tune the Operating System Kernel parameters.
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Kernel parameter
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Description
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Minimum
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Maximum
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Default
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aio_listio_max
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Specifies how many POSIX asynchronous I/O operations are allowed in a single listio() call.
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2
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65536
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256
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aio_max_ops
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Specifies the system-wide maximum number of POSIX asynchronous I/O operations that may be queued at any given time.
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1
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1048576
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2048
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aio_physmem_pct
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Percentage of physical memory that can be locked for use in POSIX asynchronous I/O operations.
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5
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50
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10
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aio_prio_delta_max
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Maximum delta that a process can decrease its asynchronous I/O priority level
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0
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20
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20
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max_async_ports
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Maximum number of ports to the asynchronous disk-I/O driver that processes can have open at any given time.
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1
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2147483647
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50
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Note:
- All configurable kernel parameters must be specified using an integer value or a formula consisting of a valid integer expression.
- The
maximum and/or default values of certain parameters may change between
releases or to vary between 32-bit and 64-bit processors.
Warning:
Changing kernel parameters to improper or inappropriate values or
combinations of values can cause data loss, system panics, or other
(possibly very obscure and/or difficult to diagnose) operating
anomalies, depending on which parameters are set to what values.
- Before altering the value of any configurable kernel parameter, be sure you know the implications of making the change.
- Never
set any system parameter to a value outside the allowable range for
that parameter (SAM refuses to store values outside of the allowable
range).
- Many parameters interact, and their values must be selected in a balanced way.
For more information about POSIX asynchronous I/O, see the HP-UX Reference entry aio(5). Please contact HP-UX OS support for more information about these parameters and their management. |
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