Need help with warn messages in sys logs

UNIX AIX
1

Hello,

Can you please look into the below warning messages on AIX sys logs ? is this related to application ? do we need to do anything from OS side ?

we're running WAS on this LPAR.

Feb 12 03:47:48 myserver user:warn|warning IBM Java[34343443]: JVMJ9VM134W The system fullcore option is set to FALSE, system dumps may be truncated.
Feb 12 03:57:24 myserver user:warn|warning IBM Java[43434343]: JVMJ9VM134W The system fullcore option is set to FALSE, system dumps may be truncated.
Feb 12 04:00:42 myserver user:warn|warning IBM Java[34343434]: JVMJ9VM134W The system fullcore option is set to FALSE, system dumps may be truncated.
Feb 12 04:00:42 myserver user:warn|warning IBM Java[434343434]:JVMJ9VM134W The system fullcore option is set to FALSE, system dumps may be truncated.
Feb 12 04:00:42 myserver user:warn|warning IBM Java[43343434]: JVMJ9VM134W The system fullcore option is set to FALSE, system dumps may be truncated.

i do not see anything on errlogs. please suggest.

2

IBM Knowledge Center

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3 
lsattr -El sys0 -a fullcore
chdev -l sys0 -a fullcore=true
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4

Thanks for your prompt response.

#lsattr -El sys0 -a fullcore
fullcore false Enable full CORE dump True

#ulimit -c
2097151

From IBM page, i see that
we need to set following settings on OS

ulimit -c unlimited         turn on corefiles with unlimited size
ulimit -n unlimited         allows an unlimited number of open file descriptors
ulimit -d unlimited         sets the user data limit to unlimited
ulimit -f unlimited         sets the file limit to unlimited

But we are running JVMs under root user.
can i still set the "corefiles with unlimited size" ?

currently it is 2097151

or is it ok to enable fullcore = true, with out changing the core to unlimited ?

please suggest.

5

the fullcore setting - which is what the syslog/errpt message was about are more specific to application/system 'crashes' that result in a machine-binary core dump.

Java has it's own style of coredumps, text if I recall, and so I suspect they fall under the fsize setting, rather than coresize.

Under normal circumstances you should not be having a lot of coredumps - so setting it unlimited should not be a concern. If you are debugging an issue having an incomplete dump (that is maybe hard to generate) is a tremendous headache - again I would go for unlimited.

When you doubt you will ever use a core for analysis - then you could keep them sized smaller than unlimited.

My opinion, hope it helps.

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6

there are two types of cores in conjunction with Java:

  • "normal" AIX cores
  • Java cores and heapdumps

fullcore and ulimit regulates "normal" AIX cores, not Java cores. If a java process dumps, it can produce just java dump and no AIX core file. In this case it doesn't matter if fullcore=yes and ulimit - = unlimited. But it can also be the other case - the process (because it is AIX process) dumps a core and Java has no idea about this dump and doesn't write its own dump. In this case it is better to have fullcore=yes and ulimit -c = unlimited.

But before setting ulimit (or better - chuser core=-1 username :wink: ask your AIX administrator. In many environments it is forbidden to produce full core dumps because of security and because the filesystem can be overflowed with dumps, if you forget to remove them.

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