Found this on IBM's website.

http://publib.boulder.ibm.com/infocenter/systems/index.jsp?topic=/com.ib
m.aix.baseadmn/doc/baseadmndita/page_space_trouble.htm

Paging space troubleshooting
The most common problem regarding paging space is caused by running out
of allocated space.

The total amount of paging space is often determined by trial and error.
One commonly used guideline is to double the RAM size and use that
figure as a paging space target. If paging space runs low, processes can
be lost, and if paging space runs out, the system can panic. The
following signal and error information can help you monitor and resolve
or prevent paging space problems.

The operating system monitors the number of free paging space blocks and
detects when a paging-space shortage exists. When the number of free
paging-space blocks falls below a threshold known as the paging-space
warning level, the system informs all processes (except kprocs) of this
condition by sending the SIGDANGER signal. If the shortage continues and
falls below a second threshold known as the paging-space kill level, the
system sends the SIGKILL signal to processes that are the major users of
paging space and that do not have a signal handler for the SIGDANGER
signal. (The default action for the SIGDANGER signal is to ignore the
signal.) The system continues sending SIGKILL signals until the number
of free paging-space blocks is above the paging-space kill level. 
Note: If the low_ps_handling parameter is set to 2 (under the vmo
command) and if no process was found to kill (without the SIGDANGER
handler), the system will send the SIGKILL signal to the youngest
processes that have a signal handler for the SIGDANGER signal. 
Processes that dynamically allocate memory can ensure that sufficient
paging space exists by monitoring the paging-space levels with the
psdanger subroutine or by using special allocation routines. You can use
the disclaim subroutine to prevent processes from ending when the
paging-space kill level is reached. To do this, define a signal handler
for the SIGDANGER signal and release memory and paging-space resources
allocated in their data and stack areas and in shared memory segments.


-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Kevin King
Sent: Tuesday, September 02, 2008 1:39 PM
To: [email protected]
Subject: [U2] SIGDANGER

Anyone seen this message and know what it means?

*Warning: Low Swap Space. SIGDANGER received.*

This is on an AIX 5.3 box running Unidata 6.1.13 and it just started
appearing this morning on a few terminals somewhat randomly.  The "df"
command doesn't report any disks in crisis and /ud/temp should have
plenty
of space.  Any ideas?

-Kevin
http://www.PrecisOnline.com
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