ora-solutions.net - Martin Decker » Linux

ACFS Filesystem Monitoring and Group Ownership

Martin — Mon, 10 Jan 2011 09:06:00 +0000

When you create an ACFS Filesystem in Grid Infrastructure 11.2.0.1 or 11.2.0.2, the filesystem root directory group ownership is set to Group SS_ASM_GRP, e.g. asmadmin.

[grid@md1 ~]$ cd /opt/oracle/gridbase/acfsmounts
[grid@md1 acfsmounts]$ ls -al
total 12
drwxr-xr-x  3 grid oinstall 4096 Jan 10 09:44 .
drwxr-xr-x 10 grid oinstall 4096 Jan 10 09:43 ..
drwxrwx---  4 root   asmadm 4096 Jan 10 09:44 data_testvol
 
SQL> select * from v$asm_filesystem where fs_name = '/opt/oracle/gridbase/acfsmounts/data_testvol'
 
FS_NAME                                        AVAILABLE BLOCK_SIZE STATE         CORRU    NUM_VOL TOTAL_SIZE TOTAL_FREE TOTAL_SNAP_SPACE_USAGE
---------------------------------------------- --------- ---------- ------------- ----- ---------- ---------- ---------- ----------------------
/opt/oracle/gridbase/acfsmounts/data_testvol   10-JAN-11          4 AVAILABLE     FALSE          1        256 119.769531                      0

If – for whatever reason – you change the group ownership from asmadm to a different group, ASM can not populate the views v$asm_filesystem and v$asm_acfsvolumes which in turn means that you can not monitor the filesystem with Oracle Enterprise Manager Grid Control because it uses those 2 views for monitoring.

[root@md1 data_testvol]# chgrp myapp .
[root@md1 data_testvol]# ls -la
total 80
drwxrwx--- 4 root   myapp     4096 Jan 10 09:45 .
drwxr-xr-x 3 grid   oinstall  4096 Jan 10 09:44 ..
drwxr-xr-x 5 root   root      4096 Jan 10 09:44 .ACFS
-rw-r--r-- 1 root   asmadm     610 Jan 10 09:45 .fslimit
drwx------ 2 root   root     65536 Jan 10 09:44 lost+found
 
 
SQL> select * from v$asm_filesystem where fs_name = '/opt/oracle/gridbase/acfsmounts/data_testvol'
  2  ;
 
no rows selected

From my point of view, this is a severe limitation. ACFS Filesystems, should like any other filesystem, be able to allow any user/group ownership and still be able to monitor it. However, I could not convince my oracle support engineer to see it the same way…

Grid Control 11g: Diagnosing OMS High CPU Utilization

Martin — Thu, 11 Nov 2010 08:03:11 +0000

Beginning with 11g Oracle Enterprise Manager Grid Control is using Weblogic instead of Oracle Application Server. I am currently experiencing very sluggish Grid Control Console performance and high CPU Utilization of EMGC_OMS1 weblogic server. This article shows how you can diagnose the problem and “assist” Oracle support in helping to solve the issue.

First step to find out what´s going on is to use “top”.

top - 08:29:12 up 4 days, 20:56,  3 users,  load average: 1.47, 1.60, 1.61
Tasks: 532 total,   1 running, 531 sleeping,   0 stopped,   0 zombie
Cpu(s):  1.3%us,  0.7%sy,  0.0%ni, 97.8%id,  0.2%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:  132033652k total, 20255244k used, 111778408k free,   728860k buffers
Swap: 20971512k total,        0k used, 20971512k free, 15391704k cached
 
  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
30181 gc11g    15   0 1778m 1.1g  49m S 99.7  0.9 626:54.30 java

PID 30181 is using 100% (and has been using it for a very long time)

It´s the EMGC_OMS1 server:

1
2

gc11g   30181 30129  9 Nov06 ?        10:27:20 /oracle/jdk/jdk1.6.0_21/bin/java -client -Xms256m -Xmx512m -XX:CompileThreshold=8000 -XX:PermSize=128m -XX:MaxPermSize=512m -Dweblogic.Name=EMGC_OMS1 -Djava.security.policy=/oracle/grid/middleware/wlserver_10.3/server/lib/weblogic.policy -Dweblogic.system.BootIdentityFile=/oracle/grid/gc_inst/user_projects/domains/GCDomain/servers/EMGC_OMS1/data/nodemanager/boot.properties -Dweblogic.nodemanager.ServiceEnabled=true -Dweblogic.security.SSL.ignoreHostnameVerification=true -Dweblogic.ReverseDNSAllowed=false -DINSTANCE_HOME=/oracle/grid/gc_inst/em/EMGC_OMS1 -DORACLE_HOME=/oracle/grid/middleware/oms11g -Ddomain.home=/oracle/grid/gc_inst/user_projects/domains/GCDomain -Djava.awt.headless=true -Ddomain.name=GCDomain -Docm.repeater.home=/oracle/grid/middleware/oms11g -Djava.security.egd=file:///dev/urandom -Xverify:none -da -Dplatform.home=/oracle/grid/middleware/wlserver_10.3 -Dwls.home=/oracle/grid/middleware/wlserver_10.3/server -Dweblogic.home=/oracle/grid/middleware/wlserver_10.3/server -Ddomain.home=/oracle/grid/gc_inst/user_projects/domains/GCDomain -Dcommon.components.home=/oracle/grid/middleware/oracle_common -Djrf.version=11.1.1 -Dorg.apache.commons.logging.Log=org.apache.commons.logging.impl.Jdk14Logger -Djrockit.optfile=/oracle/grid/middleware/oracle_common/modules/oracle.jrf_11.1.1/jrocket_optfile.txt -Doracle.domain.config.dir=/oracle/grid/gc_inst/user_projects/domains/GCDomain/config/fmwconfig -Doracle.server.config.dir=/oracle/grid/gc_inst/user_projects/domains/GCDomain/config/fmwconfig/servers/EMGC_OMS1 -Doracle.security.jps.config=/oracle/grid/gc_inst/user_projects/domains/GCDomain/config/fmwconfig/jps-config.xml -Djava.protocol.handler.pkgs=oracle.mds.net.protocol -Digf.arisidbeans.carmlloc=/oracle/grid/gc_inst/user_projects/domains/GCDomain/config/fmwconfig/carml -Digf.arisidstack.home=/oracle/grid/gc_inst/user_projects/domains/GCDomain/config/fmwconfig/arisidprovider -Dweblogic.alternateTypesDirectory=/oracle/grid/middleware/oracle_common/modules/oracle.ossoiap_11.1.1,/oracle/grid/middleware/oracle_common/modules/oracle.oamprovider_11.1.1 -Dweblogic.jdbc.remoteEnabled=false -Dweblogic.management.discover=false -Dweblogic.management.server=https://t44grid.wwk-group.com:7101 -Dwlw.iterativeDev= -Dwlw.testConsole= -Dwlw.logErrorsToConsole= -Dweblogic.ext.dirs=/oracle/grid/middleware/patch_wls1032/profiles/default/sysext_manifest_classpath weblogic.Server
oel5n1:/home/gc11g >

Next step is to find out which thread is consuming 100% of cpu.

oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30181   5
30181 gc11g   1821640 1167200 S 15 0 00:00:03  0.0 java            30182   8
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30183   0
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30184   8
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30185  11
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30186  10
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30187   3
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30188  15
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30189   9
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30190   2
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30191  13
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30192   1
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30193   4
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30194  14
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            30195   5
30181 gc11g   1821640 1167200 R 25 0 08:30:49  7.6 java            30196   2       <<<<<<
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30197  10
30181 gc11g   1821640 1167200 S 15 0 00:00:04  0.0 java            30198   4
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30199   5
30181 gc11g   1821640 1167200 S 15 0 00:00:58  0.0 java            30200  15
30181 gc11g   1821640 1167200 S 15 0 00:00:57  0.0 java            30201   2
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30202   5
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30203  13
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30204  10
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30496   4
30181 gc11g   1821640 1167200 S 15 0 00:18:50  0.2 java            30497  11
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30498  15
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30499   0
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30504   8
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30505  10
30181 gc11g   1821640 1167200 S 15 0 00:00:11  0.0 java            30510  15
30181 gc11g   1821640 1167200 S 15 0 00:00:38  0.0 java            30513  11
30181 gc11g   1821640 1167200 S 15 0 00:00:38  0.0 java            30514  13
30181 gc11g   1821640 1167200 S 15 0 00:00:37  0.0 java            30517  10
30181 gc11g   1821640 1167200 S 15 0 00:00:39  0.0 java            30518  14
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30529   0
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30533   8
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30588   8
30181 gc11g   1821640 1167200 S 15 0 00:00:01  0.0 java            30589   5
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30590  14
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30591   4
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30592   3
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30899   8
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30901   9
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30904   3
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30907  15
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            30910  12
30181 gc11g   1821640 1167200 S 15 0 00:00:02  0.0 java            31205   2
30181 gc11g   1821640 1167200 S 15 0 00:29:45  0.4 java            31526   4
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            31568  15
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            31593   5
30181 gc11g   1821640 1167200 S 15 0 00:12:02  0.1 java            31600  15
30181 gc11g   1821640 1167200 S 15 0 00:08:27  0.1 java            31601  13
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32157   4
30181 gc11g   1821640 1167200 S 15 0 00:00:01  0.0 java            32160   2
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32161  12
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32163   2
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32166  11
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32168   0
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32169  13
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32170  10
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32171  10
30181 gc11g   1821640 1167200 S 16 0 00:00:00  0.0 java            32172   3
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32173  10
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32174   8
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32175  13
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32176  12
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32177   0
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32178   9
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32179  13
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32180   9
30181 gc11g   1821640 1167200 S 15 0 00:00:01  0.0 java            32181   6
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32182   0
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32183   8
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32264  15
30181 gc11g   1821640 1167200 S 15 0 00:01:02  0.0 java            32265   8
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32269   8
30181 gc11g   1821640 1167200 S 15 0 00:00:12  0.0 java            32270   1
30181 gc11g   1821640 1167200 S 15 0 00:00:14  0.0 java            32271   6
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32275  10
30181 gc11g   1821640 1167200 S 15 0 00:00:15  0.0 java            32280  15
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32283  12
30181 gc11g   1821640 1167200 S 15 0 00:10:45  0.1 java            32286  13
30181 gc11g   1821640 1167200 S 15 0 00:00:47  0.0 java            32289  12
30181 gc11g   1821640 1167200 S 15 0 00:02:57  0.0 java            32295   0
30181 gc11g   1821640 1167200 S 15 0 00:00:03  0.0 java            32297  12
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32301   9
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32302  12
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32305   5
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32306  12
30181 gc11g   1821640 1167200 S 15 0 00:01:09  0.0 java            32307   7
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32308   2
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32309   0
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32310   4
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32311   8
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32326  13
30181 gc11g   1821640 1167200 S 15 0 00:00:14  0.0 java            32327  11
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32336  13
30181 gc11g   1821640 1167200 S 15 0 00:00:01  0.0 java            32337   8
30181 gc11g   1821640 1167200 S 15 0 00:00:29  0.0 java            32338   3
30181 gc11g   1821640 1167200 S 15 0 00:00:05  0.0 java            32339   9
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32340  10
30181 gc11g   1821640 1167200 S 15 0 00:00:18  0.0 java            32341  12
30181 gc11g   1821640 1167200 S 15 0 00:00:02  0.0 java            32342   7
30181 gc11g   1821640 1167200 S 15 0 00:00:29  0.0 java            32343   7
30181 gc11g   1821640 1167200 S 15 0 00:00:10  0.0 java            32344   0
30181 gc11g   1821640 1167200 S 15 0 00:00:05  0.0 java            32351   0
30181 gc11g   1821640 1167200 S 15 0 00:00:02  0.0 java             1943   9
30181 gc11g   1821640 1167200 S 15 0 00:01:19  0.0 java             1944   6
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java             1945  15
30181 gc11g   1821640 1167200 S 15 0 00:00:06  0.0 java             1946  11
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java             2890  15
30181 gc11g   1821640 1167200 S 15 0 00:02:56  0.0 java             7839  14
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            10208   0
30181 gc11g   1821640 1167200 S 15 0 00:00:02  0.0 java            16818  15
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            18310   2
30181 gc11g   1821640 1167200 S 15 0 00:00:09  0.0 java              642  14
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java              690   7
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            27517   8
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            27518   8
30181 gc11g   1821640 1167200 S 15 0 00:00:01  0.0 java            29228   3
30181 gc11g   1821640 1167200 S 15 0 00:02:46  0.1 java            12075  12
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            12160   1
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            12829  13
30181 gc11g   1821640 1167200 S 15 0 00:00:02  0.0 java             2773   7
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            14748  14
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            14749   6
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            14750   1
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            14751   0
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            14752   5
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            14753   5
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            14860  12
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            16706   8
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            17312   1
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            17313  12
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            17425  12
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            17426  15
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            19993  12
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            19994  15
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            19995  12
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java             3575   9
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            16593  14
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            18488   8
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            18489   5
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            21901   7
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java             5572   7
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java             7993   9
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            27543  13
30181 gc11g   1821640 1167200 S 15 0 00:00:00  0.0 java            32075  15

So, it is thread 30196 of PID 30181. Let´s remove the ” sleeping ” threads with grep.

oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181 | grep -v " S "
30181 gc11g   1821640 1167200 R 25 0 08:31:37  7.7 java            30196   6
oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181 | grep -v " S "
30181 gc11g   1821640 1167200 R 25 0 08:31:39  7.7 java            30196   2
oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181 | grep -v " S "
30181 gc11g   1821640 1167200 R 25 0 08:31:40  7.7 java            30196   2
oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181 | grep -v " S "
30181 gc11g   1821640 1167200 R 18 0 08:31:40  7.7 java            30196   2
oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181 | grep -v " S "
30181 gc11g   1821640 1167200 R 18 0 08:31:41  7.7 java            30196  15
oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181 | grep -v " S "
30181 gc11g   1821640 1167200 R 19 0 08:31:41  7.7 java            30196  15
oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181 | grep -v " S "
30181 gc11g   1821640 1167200 R 20 0 08:31:42  7.7 java            30196  13
oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181 | grep -v " S "
30181 gc11g   1821640 1167200 R 20 0 08:31:42  7.7 java            30196   9
oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181 | grep -v " S "
30181 gc11g   1821640 1167200 R 21 0 08:31:42  7.7 java            30196   9
oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181 | grep -v " S "
30181 gc11g   1821640 1167200 R 21 0 08:31:43  7.7 java            30196   9
oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181 | grep -v " S "
30181 gc11g   1821640 1167200 R 23 0 08:31:43  7.7 java            30196   9
oel5n1:/home/gc11g >  ps -Leo pid,ruser,vsz,rss,state,priority,nice,time,%cpu,comm,lwp,psr | grep 30181 | grep -v " S "
30181 gc11g   1821640 1167200 R 24 0 08:31:43  7.7 java            30196   9

It is always the same thread which is using 7.7% (~1/16 cores) of the all the CPU´s on the system.

let´s take a pstack:

1	oel5n1:/home/gc11g > pstack 30181

let´s grep for the LWP we know:

oel5n1:/home/gc11g > pstack 30181 | grep -A 20 30196
 
Thread 135 (Thread 0x4024f940 (LWP 30196)):                           <<<<<<<<<<<<<<<<<<
#0  0x00002b7471e17d3f in instanceKlass::oop_follow_contents ()
#1  0x00002b747203e6c3 in objArrayKlass::oop_follow_contents ()
#2  0x00002b7471fee5e3 in MarkSweep::follow_stack ()
#3  0x00002b7472094964 in PSMarkSweep::mark_sweep_phase1 ()
#4  0x00002b7472093859 in PSMarkSweep::invoke_no_policy ()
#5  0x00002b74720a0737 in PSScavenge::invoke ()
#6  0x00002b747206814e in ParallelScavengeHeap::failed_mem_allocate ()
#7  0x00002b747218fbc9 in VM_ParallelGCFailedAllocation::doit ()
#8  0x00002b747219ccfa in VM_Operation::evaluate ()
#9  0x00002b747219c312 in VMThread::evaluate_operation ()
#10 0x00002b747219c583 in VMThread::loop ()
#11 0x00002b747219c08e in VMThread::run ()
#12 0x00002b74720560df in java_start ()
#13 0x0000003130e064a7 in start_thread () from /lib64/libpthread.so.0
#14 0x00000031302d3c2d in clone () from /lib64/libc.so.6
 
 
oel5n1:/home/gc11g > pstack 30181 | grep -A 20 30196
Thread 135 (Thread 0x4024f940 (LWP 30196)):
#0  0x00002b7471e17d3f in instanceKlass::oop_follow_contents ()
#1  0x00002b747203e6c3 in objArrayKlass::oop_follow_contents ()
#2  0x00002b7471fee5e3 in MarkSweep::follow_stack ()
#3  0x00002b7472094964 in PSMarkSweep::mark_sweep_phase1 ()
#4  0x00002b7472093859 in PSMarkSweep::invoke_no_policy ()
#5  0x00002b74720a0737 in PSScavenge::invoke ()
#6  0x00002b747206814e in ParallelScavengeHeap::failed_mem_allocate ()
#7  0x00002b747218fbc9 in VM_ParallelGCFailedAllocation::doit ()
#8  0x00002b747219ccfa in VM_Operation::evaluate ()
#9  0x00002b747219c312 in VMThread::evaluate_operation ()
#10 0x00002b747219c583 in VMThread::loop ()
#11 0x00002b747219c08e in VMThread::run ()
#12 0x00002b74720560df in java_start ()
#13 0x0000003130e064a7 in start_thread () from /lib64/libpthread.so.0
#14 0x00000031302d3c2d in clone () from /lib64/libc.so.6
 
 
 
oel5n1:/home/gc11g > pstack 30181 | grep -A 20 30196
Thread 135 (Thread 0x4024f940 (LWP 30196)):
#0  0x00002b7472046d27 in objArrayKlass::oop_adjust_pointers ()
#1  0x00002b747209549e in PSMarkSweepDecorator::adjust_pointers ()
#2  0x00002b74720967f0 in PSOldGen::adjust_pointers ()
#3  0x00002b7472094c3a in PSMarkSweep::mark_sweep_phase3 ()
#4  0x00002b74720938f6 in PSMarkSweep::invoke_no_policy ()
#5  0x00002b74720a0737 in PSScavenge::invoke ()
#6  0x00002b747206814e in ParallelScavengeHeap::failed_mem_allocate ()
#7  0x00002b747218fbc9 in VM_ParallelGCFailedAllocation::doit ()
#8  0x00002b747219ccfa in VM_Operation::evaluate ()
#9  0x00002b747219c312 in VMThread::evaluate_operation ()
#10 0x00002b747219c583 in VMThread::loop ()
#11 0x00002b747219c08e in VMThread::run ()
#12 0x00002b74720560df in java_start ()
#13 0x0000003130e064a7 in start_thread () from /lib64/libpthread.so.0
#14 0x00000031302d3c2d in clone () from /lib64/libc.so.6
 
 
oel5n1:/home/gc11g > pstack 30181 | grep -A 20 30196
Thread 135 (Thread 0x4024f940 (LWP 30196)):
#0  0x00002b7471fee9d3 in MarkSweep::IsAliveClosure::do_object_b ()
#1  0x00002b7471dfad18 in Hashtable::unlink ()
#2  0x00002b74720949ef in PSMarkSweep::mark_sweep_phase1 ()
#3  0x00002b7472093859 in PSMarkSweep::invoke_no_policy ()
#4  0x00002b74720a0737 in PSScavenge::invoke ()
#5  0x00002b747206814e in ParallelScavengeHeap::failed_mem_allocate ()
#6  0x00002b747218fbc9 in VM_ParallelGCFailedAllocation::doit ()
#7  0x00002b747219ccfa in VM_Operation::evaluate ()
#8  0x00002b747219c312 in VMThread::evaluate_operation ()
#9  0x00002b747219c583 in VMThread::loop ()
#10 0x00002b747219c08e in VMThread::run ()
#11 0x00002b74720560df in java_start ()
#12 0x0000003130e064a7 in start_thread () from /lib64/libpthread.so.0
#13 0x00000031302d3c2d in clone () from /lib64/libc.so.6
 
 
oel5n1:/home/gc11g > pstack 30181 | grep -A 20 30196
Thread 135 (Thread 0x4024f940 (LWP 30196)):
#0  0x00002b7471fee706 in MarkSweep::AdjustPointerClosure::do_oop ()
#1  0x00002b7471dfadb1 in Hashtable::oops_do ()
#2  0x00002b7472094bf9 in PSMarkSweep::mark_sweep_phase3 ()
#3  0x00002b74720938f6 in PSMarkSweep::invoke_no_policy ()
#4  0x00002b74720a0737 in PSScavenge::invoke ()
#5  0x00002b747206814e in ParallelScavengeHeap::failed_mem_allocate ()
#6  0x00002b747218fbc9 in VM_ParallelGCFailedAllocation::doit ()
#7  0x00002b747219ccfa in VM_Operation::evaluate ()
#8  0x00002b747219c312 in VMThread::evaluate_operation ()
#9  0x00002b747219c583 in VMThread::loop ()
#10 0x00002b747219c08e in VMThread::run ()
#11 0x00002b74720560df in java_start ()
#12 0x0000003130e064a7 in start_thread () from /lib64/libpthread.so.0
#13 0x00000031302d3c2d in clone () from /lib64/libc.so.6
 
 
oel5n1:/home/gc11g > pstack 30181 | grep -A 20 30196
Thread 135 (Thread 0x4024f940 (LWP 30196)):
#0  0x00002b7471e179e5 in instanceKlass::adjust_static_fields ()
#1  0x00002b7471e234ad in instanceKlassKlass::oop_adjust_pointers ()
#2  0x00002b747209549e in PSMarkSweepDecorator::adjust_pointers ()
#3  0x00002b74720967f0 in PSOldGen::adjust_pointers ()
#4  0x00002b7472094c3a in PSMarkSweep::mark_sweep_phase3 ()
#5  0x00002b74720938f6 in PSMarkSweep::invoke_no_policy ()
#6  0x00002b74720a0737 in PSScavenge::invoke ()
#7  0x00002b747206814e in ParallelScavengeHeap::failed_mem_allocate ()
#8  0x00002b747218fbc9 in VM_ParallelGCFailedAllocation::doit ()
#9  0x00002b747219ccfa in VM_Operation::evaluate ()
#10 0x00002b747219c312 in VMThread::evaluate_operation ()
#11 0x00002b747219c583 in VMThread::loop ()
#12 0x00002b747219c08e in VMThread::run ()
#13 0x00002b74720560df in java_start ()
#14 0x0000003130e064a7 in start_thread () from /lib64/libpthread.so.0
#15 0x00000031302d3c2d in clone () from /lib64/libc.so.6
 
 
oel5n1:/home/gc11g > pstack 30181 | grep -A 20 30196
Thread 135 (Thread 0x4024f940 (LWP 30196)):
#0  0x00002b7471e17e54 in instanceKlass::oop_follow_contents ()
#1  0x00002b747203e6c3 in objArrayKlass::oop_follow_contents ()
#2  0x00002b7471fee5e3 in MarkSweep::follow_stack ()
#3  0x00002b7472094964 in PSMarkSweep::mark_sweep_phase1 ()
#4  0x00002b7472093859 in PSMarkSweep::invoke_no_policy ()
#5  0x00002b74720a0737 in PSScavenge::invoke ()
#6  0x00002b747206814e in ParallelScavengeHeap::failed_mem_allocate ()
#7  0x00002b747218fbc9 in VM_ParallelGCFailedAllocation::doit ()
#8  0x00002b747219ccfa in VM_Operation::evaluate ()
#9  0x00002b747219c312 in VMThread::evaluate_operation ()
#10 0x00002b747219c583 in VMThread::loop ()
#11 0x00002b747219c08e in VMThread::run ()
#12 0x00002b74720560df in java_start ()
#13 0x0000003130e064a7 in start_thread () from /lib64/libpthread.so.0
#14 0x00000031302d3c2d in clone () from /lib64/libc.so.6
 
 
oel5n1:/home/gc11g > pstack 30181 | grep -A 20 30196
Thread 135 (Thread 0x4024f940 (LWP 30196)):
#0  0x00002b747203e640 in objArrayKlass::oop_follow_contents ()
#1  0x00002b7471fee5e3 in MarkSweep::follow_stack ()
#2  0x00002b7472094964 in PSMarkSweep::mark_sweep_phase1 ()
#3  0x00002b7472093859 in PSMarkSweep::invoke_no_policy ()
#4  0x00002b74720a0737 in PSScavenge::invoke ()
#5  0x00002b747206814e in ParallelScavengeHeap::failed_mem_allocate ()
#6  0x00002b747218fbc9 in VM_ParallelGCFailedAllocation::doit ()
#7  0x00002b747219ccfa in VM_Operation::evaluate ()
#8  0x00002b747219c312 in VMThread::evaluate_operation ()
#9  0x00002b747219c583 in VMThread::loop ()
#10 0x00002b747219c08e in VMThread::run ()
#11 0x00002b74720560df in java_start ()
#12 0x0000003130e064a7 in start_thread () from /lib64/libpthread.so.0
#13 0x00000031302d3c2d in clone () from /lib64/libc.so.6
 
 
 
oel5n1:/home/gc11g > pstack 30181 | grep -A 20 30196
Thread 135 (Thread 0x4024f940 (LWP 30196)):
#0  0x00002b7471d50445 in ConstantPoolCacheEntry::follow_contents ()
#1  0x00002b7471d4f4f6 in constantPoolCacheKlass::oop_follow_contents ()
#2  0x00002b7471fee5e3 in MarkSweep::follow_stack ()
#3  0x00002b7472094964 in PSMarkSweep::mark_sweep_phase1 ()
#4  0x00002b7472093859 in PSMarkSweep::invoke_no_policy ()
#5  0x00002b74720a0737 in PSScavenge::invoke ()
#6  0x00002b747206814e in ParallelScavengeHeap::failed_mem_allocate ()
#7  0x00002b747218fbc9 in VM_ParallelGCFailedAllocation::doit ()
#8  0x00002b747219ccfa in VM_Operation::evaluate ()
#9  0x00002b747219c312 in VMThread::evaluate_operation ()
#10 0x00002b747219c583 in VMThread::loop ()
#11 0x00002b747219c08e in VMThread::run ()
#12 0x00002b74720560df in java_start ()
#13 0x0000003130e064a7 in start_thread () from /lib64/libpthread.so.0
#14 0x00000031302d3c2d in clone () from /lib64/libc.so.6
 
oel5n1:/home/gc11g > pstack 30181 | grep -A 20 30196
Thread 135 (Thread 0x4024f940 (LWP 30196)):
#0  0x00002b7471f8af28 in klassKlass::oop_follow_contents ()
#1  0x00002b7471e226cc in instanceKlassKlass::oop_follow_contents ()
#2  0x00002b7471fee5e3 in MarkSweep::follow_stack ()
#3  0x00002b7472094964 in PSMarkSweep::mark_sweep_phase1 ()
#4  0x00002b7472093859 in PSMarkSweep::invoke_no_policy ()
#5  0x00002b74720a0737 in PSScavenge::invoke ()
#6  0x00002b747206814e in ParallelScavengeHeap::failed_mem_allocate ()
#7  0x00002b747218fbc9 in VM_ParallelGCFailedAllocation::doit ()
#8  0x00002b747219ccfa in VM_Operation::evaluate ()
#9  0x00002b747219c312 in VMThread::evaluate_operation ()
#10 0x00002b747219c583 in VMThread::loop ()
#11 0x00002b747219c08e in VMThread::run ()
#12 0x00002b74720560df in java_start ()
#13 0x0000003130e064a7 in start_thread () from /lib64/libpthread.so.0
#14 0x00000031302d3c2d in clone () from /lib64/libc.so.6

I´m not much of a Java guy, but this tells me that the thread is doing ParallelGC. So, the issue might be related to a configuration of too small Heap size. (Xmx) I will talk with support to decide whether they support to have Xmx increased to 1G or 2G. In case the cpu consumption is not for Garbage Collection but some other OEM code, then there is a command “emctl dump omsthread”, which can be used:

oel5n1:/home/gc11g > emctl dump omsthread
Oracle Enterprise Manager 11g Release 1 Grid Control
Copyright (c) 1996, 2010 Oracle Corporation.  All rights reserved.
Thread dumped successfully for process '30181' to log file 
/oracle/grid/gc_inst/user_projects/domains/GCDomain/servers/EMGC_OMS1/logs/EMGC_OMS1.out

If we calculate LWP 30196 from dec to hex, we get 75f5, this is NID from OMS thread dump.

"Reference Handler" daemon prio=10 tid=0x000000004fdff000 nid=0x75f5 waiting for monitor entry [0x0000000040725000]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:108)
        - waiting to lock <0x00002aaacf4967a0> (a java.lang.ref.Reference$Lock)

Update 26.11.2010:

Oracle support has recommended to increase Xms/Xmx to 1024m and check whether that is sufficient. This has to be changed in file gc_inst/user_projects/domains/GCDomain/bin/setDomainEnv.sh and in those variables for Linux 64bit:

XMS_SUN_64BIT="1024"
XMX_SUN_64BIT="1024"

Upgrade/Install of Grid Infrastructure to 11.2.0.2 is failing

Martin — Wed, 29 Sep 2010 07:36:58 +0000

I have come across a quite difficult issue when trying to install/upgrade to Grid Infrastructure 11.2.0.2 on Linux. We have performed the following trials:

Installation of 11.1.0.6 to have Cluster Files (OCR/Votedisk) outside of ASM, then upgrade to 11.2.0.1. After that, we installed all the latest patches (PSU 11.2.0.1.2). Firstly we considered running RDBMS 11.1.0.7 in a 11.2 Grid Infrastructure cluster. However, there are quite a few issues when running this mixed setup. For most of them, patches or workarounds do exist. (see Note 948456.1) However, during failover testing, we realized that the remote database instance does not survive the failure of the public lan of the local node. This is fixed in 11.2.0.2 which motivated us to upgrade.
We tried to upgrade our GI 11.2.0.1.2 installation to 11.2.0.2. Everything went fine until it failed when running rootupgrade.sh on the last (second) node. Here, the second node could not join the cluster. Important to know is that 11.2.0.2 brings the new feature HAIP (High available IP), which allows to have multiple private interconnect interfaces (each with a different private interconnect network ip) to be used for failover/load balancing by Grid Infrastructure. For this feature, Oracle uses Multicast on network “230.0.1.0″. This is stated in the updated version of the README for Oracle Database 11.2: http://download.oracle.com/docs/cd/E11882_01/readmes.112/e17129/toc.htm#CHDIEHCH

ACFS-9309: ADVM/ACFS installation correctness verified.
Failed to start Oracle Clusterware stack
Failed to start Cluster Synchorinisation Service in clustered mode at
/opt/oracle/grid11/11.2.0.2/grid/crs/install/crsconfig_lib.pm line 1016.
/opt/oracle/grid11/11.2.0.2/grid/perl/bin/perl -I/opt/oracle/grid11/11.2.0.2/grid/perl/lib -
I/opt/oracle/grid11/11.2.0.2/grid/crs/install
/opt/oracle/grid11/11.2.0.2/grid/crs/install/rootcrs.pl execution failed

The next try was to remove everything and directly install 11.2.0.1 with cluster files stored inside of ASM. This worked fine and we then proceeded in patching with latest PSU 11.2.0.1.2. Then, we gave it another try to upgrade to 11.2.0.2. The same problem occurred again at rootupgrade.sh on second node.
Then we decided to remove everything again and try a direct installation of 11.2.0.2 without any upgrade. This also failed at root.sh on last node.

With the hints of several colleagues from OTN forum (http://forums.oracle.com/forums/messageview.jspa?messageID=5393319&stqc=true) we realized that it might be related to multicast setup. We verified that multicast works with the script from MetaLink Note 413783.1. However this script does not take into account that we want multicasting via private interconnect interface instead of public LAN.

I realized that it might be necessary to add a network route to our system to direct multicast to the private interconnect network:

e.g.: /sbin/route add -net 224.0.0.0 netmask 240.0.0.0 dev bond1

After doing that, the multicast test script from MOS succeeded.

starting receiver:

[grid11@Node2 ]$ java MultiCastTestReceive

starting sender:

[grid11@Node1 ]$ java MultiCastTestSend
Sent 10 bytes to /230.0.1.0

message received by receiver:

Received data from: /10.128.128.1:13139 with length: 10

Please note that in this case 10.128.128.1 is private interconnect ip. Although it is currently just a strong suspicion, I am quite positive that this was the problem and we will consider retrying the upgrade if time allows and will report the results.

Unfortunately, Oracle support was of no help at all with this problem.

Oracle Clusterware / ASM 11.1.0.7: ASM Instance crash

Martin — Wed, 28 Oct 2009 15:27:00 +0000

During a 11gR1 Clusterware installation for a Single Instance Failover Cluster at a customer site, I have experienced an interesting behaviour, which was caused by an Oracle Bug.

The environment was:

2 Node Oracle Clusterware 11.1.0.7 Cluster on Linux x86_64 using latest Recommended Patches as of October 19th. (pre PSU 11.1.0.7.1)
Clusterware installed as unix user crs
ASM installed as unix user oracle

The ASM instances could be started with SQL*Plus without any problems, but if the ASM instances were started by means of clusterware using srvctl (either from root, crs or oracle) the ASM instances would crash at diskgroup mount with:

ORA-07445: exception encountered: core dump  [sskgds_find_rtn_hdr()+1171]
[SIGBUS] [ADDR:0x2AACD701342C] [PC:0x25799DF]
[Non-existent physical address] []

Oracle Support identified this behaviour as Bug 6952915, for which there are patches for Linux x86, x86_64 and Solaris Sparc64.

Oracle Database version 11g Release 2 for Linux finally released

Martin — Wed, 02 Sep 2009 05:38:42 +0000

Yesterday, on September 1st, Oracle released the much awaited database version 11gR2 for Linux x86 for both 32bit and 64bit platforms. The software can be downloaded via OTN: http://www.oracle.com/technology/software/products/database/index.html.

Out-of-Memory killer on 32bit Linux with big RAM

Martin — Tue, 25 Aug 2009 13:27:30 +0000

It is not very known that you can run into serious problems if you run Linux x86-32bit with a big amount of RAM installed, if using RHEL below 5. The official name for the issue is called “Low Memory Starvation”. The best solution is to use x86-64bit to be able to address the whole amount of RAM efficiently.

However, if that is not feasible, then make sure that you at least run the hugemem kernel if you use RHEL < 5. In RHEL5-32bit, the hugemem kernel is default.

A quick demonstration about what can happen if you don´t use hugemem kernel is shown here:

We realized that RMAN backup is taking more than 24 hours. Querying v$session, we find out that
one session is in ACTION "STARTED", whereas the other sessions are FINISHED.

SQL> select program, module,action
      from v$session
      where username = 'SYS' and program like 'rman%'
/      

PROGRAM                    MODULE                       ACTION
-------------------------- ---------------------------  -------------------
rman@ora-vm1 (TNS V1-V3)    backup full datafile        0000078 FINISHED129
rman@ora-vm1 (TNS V1-V3)    backup full datafile        0000272 STARTED16
rman@ora-vm1 (TNS V1-V3)    backup full datafile        0000084 FINISHED129
rman@ora-vm1 (TNS V1-V3)    rman@ora-vm1 (TNS V1-V3)
rman@ora-vm1 (TNS V1-V3)    rman@ora-vm1 (TNS V1-V3)    0000004 FINISHED131
rman@ora-vm1 (TNS V1-V3)    backup full datafile        0000092 FINISHED129

Then we check the SID,serial# from v$session of this session and also query the UNIX PID from v$process.spid

SQL> select sid,serial# from v$session where event like 'RMAN%';

       SID    SERIAL#
---------- ----------
      4343       5837

We activate SQL Tracing for this session to determine its activity:

SQL> select spid from v$process where addr =
   (select paddr from v$session where sid = 4343);

SPID
------------
1681

SQL> begin dbms_monitor.session_trace_enable(4343,5837,true,true);
  2  end;
  3  /

However, no trace file gets created. Then we start tracing system calls with strace:

ora-vm1:# strace -fp 1681
attach: ptrace(PTRACE_ATTACH, ...): Operation not permitted

“Not permitted”? – Although I am connected as root?

ps -ef|grep 1681
oracle    1681 1582  0 Aug24 ?        00:00:09 [oracle]

The linux command “ps” reports the server process as “defunct”.

ora-vm1:/usr/oracle/admin/labo/udump$ ps -ef|grep 1582
oracle   1582 21578  0 Aug24 ?        00:00:02 rman oracle/product/10.2.0/bin/rman nocatalog
oracle   21663 1582  0 Aug24 ?        00:00:01 oraclelabo (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq)))
oracle   21665 1582  0 Aug24 ?        00:00:03 oraclelabo (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq)))
oracle   1681 1582   0 Aug24 ?        00:00:09 [oracle] 
oracle   21691 1582  0 Aug24 ?        00:01:36 oraclelabo (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq)))
oracle   21695 1582  0 Aug24 ?        00:01:41 oraclelabo (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq)))
oracle   21793 1582  0 Aug24 ?        00:01:30 oraclelabo (DESCRIPTION=(LOCAL=YES)(ADDRESS=(PROTOCOL=beq)))

Next, I checked logfile /var/log/messages.1 and realized that the kernel out-of-memory killer (OOM) killed this PID because of low memory starvation.

/var/log/messages.1:
Aug  24 22:32:44 ora-vm1 kernel: Out of Memory: Killed process 1681 (oracle).

Multipathing Configuration issue waiting to happen

Martin — Wed, 05 Aug 2009 20:52:49 +0000

Quite some time ago, I came across a quite hard to find issue during a consulting engagement, which i find worth mentioning. A 2 node RAC cluster running on RHEL4 x86-64 was relocated to a different data center. Apart from making sure, that the switch ports and Fibre Channel Ports are available on the new location, there is not much to worry about.

After the relocation, on one node the multipathing configuration, implemented with dev-mapper-multipath would not work. The command “multipath -ll” would just not return any output. After more than an hour, we pinned the issue down to the error message:

# multipath -v 3
#
# all paths in cache :
#
…
…
…
path sdh not found in pathvec

When checking what device sdh was, we realized that this was a KVM device, plugged in by the sysadmins.

May 27 14:46:26 host1 kernel: Attached scsi removable disk sdh at scsi10, channel 0, id 0, lun 0
May 27 14:46:26 host1 kernel: Type: Direct-Access ANSI SCSI revision: 02
May 27 14:46:26 host1 kernel: Vendor: KVM Model: vmDisk Rev: 0.01
May 27 14:46:26 host1 kernel: scsi10 : SCSI emulation for USB Mass Storage devices
May 27 14:46:26 host1 kernel: sr1: scsi3-mmc drive: 0x/0x caddy
May 27 14:46:26 host1 kernel: Type: CD-ROM ANSI SCSI revision: 02
May 27 14:46:26 host1 kernel: Vendor: KVM Model: vmDisk-CD Rev: 0.01

BTW: What is a KVM device?
Wikipedia states: A KVM switch (with KVM being an abbreviation for Keyboard, Video or Visual Display Unit, Mouse) is a hardware device that allows a user to control multiple computers from a single keyboard, video monitor and mouse.

We then added the device sdh to the multipath blacklist section in /etc/multipath.conf, and the problem was solved:

devnode_blacklist {
devnode “^sdh$”
}

Your experience with RAC Dynamic Remastering (DRM) in 10gR2?

Martin — Tue, 12 May 2009 14:37:48 +0000

One of my customers is having severe RAC performance issues, which appeared a dozen times so far. Each time, the performance impact lasted around 10 minutes and caused basically a hang of the application. ASH investigation revealed that the time frame of performance issues exactly matches a DRM operation of the biggest segment of the database. During the problematic time period, there are 20-50 instead of 5-10 active sessions and they are mostly waiting for gc related events: “gc buffer busy”,”gc cr block busy”, “gc cr block 2-way”, “gc current block 2-way”, “gc current request”, “gc current grant busy”, etc.

In addition, there is one single session which has wait event “kjbdrmcvtq lmon drm quiesce: ping completion” (on instance 1) and 1-3 sessions with wait event “gc remaster“. (on instance 2) The cur_obj# of the session waiting on “gc remaster” is pointing to the segment being remastered.

Does anybody have any experience with DRM problems with 10.2.0.4 on Linux Itanium?

I know that it is possible to deactive DRM, but usually it should be beneficial to have it enabled. I could not find any reports of performance impact during DRM operation on metalink. Support is involved but clueless so far.

Regards,
Martin

http://forums.oracle.com/forums/message.jspa?messageID=3447436#3447436

Session waiting for “enq: RO – fast object reuse” – DBWR Process spinning on CPU

Martin — Tue, 20 Jan 2009 16:07:08 +0000

I have encountered the following problem on a 10.2.0.4 database on Linux x86_64 today:
A user session has been waiting for “enq: RO – fast object reuse” for almost 60 minutes while executing a “truncate table” SQL statement.

SQL> select username, event, sql_id, taddr, last_call_et from v$session where sid = 234;

USERNAME EVENT SQL_ID TADDR LAST_CALL_ET
———- —————————– ————- —————- ————
MD enq: RO – fast object reuse ljk299jlkj003 0000000153264570 3542

SQL> select sql_text from v$sqlstats where sql_id = ‘ljk299jlkj003′;

SQL_TEXT
————————————-
truncate table tab1

The Session was blocked by the CKPT process:

SQL> select * from dba_waiters;

WAITING_SESSION HOLDING_SESSION LOCK_TYPE MODE_HELD MODE_REQUESTED LOCK_ID1 LOCK_ID2
————— ————— ————————– —————————————- —————————————- ———- ———-
234 423 RO Row-S (SS) Exclusive 65573 1

SQL> select sid, serial#, sql_id, last_call_et, machine, program, username from v$session where sid = 423;

SID SERIAL# SQL_ID LAST_CALL_ET MACHINE PROGRAM
———- ———- ————- ———— —————- ——————————–
423 1 4133636 ora-vm1.intra oracle@ora-vm1.intra (CKPT)

The checkpoint process was waiting for database writer DBWR process, which was spinning on one cpu:

top

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
10712 oracle 25 0 2201m 1.7g 1.7g R 99.5 21.7 108:18.03 oracle

PID 10712 maps to DBW0:

[oracle@ora-vm1 ]$ ps -ef|grep 10712
oracle 10712 1 0 2008 ? 03:23:05 ora_dbw0_MDDB01

mpstat

Linux 2.6.9-78.ELsmp (ora-vm1.intra) 01/20/2009

02:21:56 PM CPU %user %nice %system %iowait %irq %soft %idle intr/s
02:21:57 PM all 49.75 0.00 0.00 0.00 0.00 0.00 50.25 1055.00
02:21:57 PM 0 0.00 0.00 0.00 0.00 0.00 0.00 100.00 1006.00
02:21:57 PM 1 100.00 0.00 0.00 0.00 0.00 0.00 0.00 49.00

02:21:57 PM CPU %user %nice %system %iowait %irq %soft %idle intr/s
02:21:58 PM all 50.75 0.00 0.00 0.50 0.00 0.00 48.76 1161.00
02:21:58 PM 0 1.00 0.00 0.00 1.00 0.00 0.00 98.00 1087.00
02:21:58 PM 1 100.00 0.00 0.00 0.00 0.00 0.00 0.00 74.00

The stack of dbw0 during the time showed these signatures:

[oracle@ora-vm1 oracle]$ pstack 10712
#0 0x000000000074b7fb in kslfre ()
#1 0x00000000010ccc3b in kcbo_exam_buf ()
#2 0x00000000010d0d62 in kcbo_service_ockpt ()
#3 0x0000000001080cd7 in kcbbdrv ()
#4 0x00000000007ddcc2 in ksbabs ()
#5 0x00000000007e4b32 in ksbrdp ()
#6 0x0000000002efcb50 in opirip ()
#7 0x00000000012da326 in opidrv ()
#8 0x0000000001e62456 in sou2o ()
#9 0x00000000006d2555 in opimai_real ()
#10 0x00000000006d240c in main ()
[oracle@ora-vm1 oracle]$ pstack 10712
#0 0x000000000074b36d in kslfre ()
#1 0x00000000010cc203 in kcbo_write_process ()
#2 0x00000000010ce608 in kcbo_write_q ()
#3 0x0000000001080a6d in kcbbdrv ()
#4 0x00000000007ddcc2 in ksbabs ()
#5 0x00000000007e4b32 in ksbrdp ()
#6 0x0000000002efcb50 in opirip ()
#7 0x00000000012da326 in opidrv ()
#8 0x0000000001e62456 in sou2o ()
#9 0x00000000006d2555 in opimai_real ()
#10 0x00000000006d240c in main ()
[oracle@ora-vm1 oracle]$ pstack 10712
#0 0x00000000010ccb60 in kcbo_exam_buf ()
#1 0x00000000010d0d62 in kcbo_service_ockpt ()
#2 0x0000000001080cd7 in kcbbdrv ()
#3 0x00000000007ddcc2 in ksbabs ()
#4 0x00000000007e4b32 in ksbrdp ()
#5 0x0000000002efcb50 in opirip ()
#6 0x00000000012da326 in opidrv ()
#7 0x0000000001e62456 in sou2o ()
#8 0x00000000006d2555 in opimai_real ()
#9 0x00000000006d240c in main ()
[oracle@ora-vm1 oracle]$ pstack 10712
#0 0x00000000010d0da5 in kcbo_service_ockpt ()
#1 0x0000000001080cd7 in kcbbdrv ()
#2 0x00000000007ddcc2 in ksbabs ()
#3 0x00000000007e4b32 in ksbrdp ()
#4 0x0000000002efcb50 in opirip ()
#5 0x00000000012da326 in opidrv ()
#6 0x0000000001e62456 in sou2o ()
#7 0x00000000006d2555 in opimai_real ()
#8 0x00000000006d240c in main ()

A MetaLink Research for the term “kcbo_service_ockpt” leads to Bug 7376934, which is a duplicate of Bug 7385253 – DBWR IS CONSUMING HIGH CPU.

Patch 7385253 is available for Linux x86_64, HP-UX, Solaris, AIX.
Reference:
MetaLink Note 762085.1 – Subject: ‘enq: RO – fast object reuse’ contention when gathering schema/table statistics in parallel

Hugepages revisited II: Be aware of kernel bugs!

Martin — Wed, 07 Jan 2009 11:31:08 +0000

It is well known that hugepages can reduce the overhead of managing memory pages of Oracle SGA by the operating system thus leading to lower system cpu utilization. I have written two blog entries regarding this topic already: Listener Coredumps on heavy load system and Hugepages revisited.

However, there is a potential risk with it: Certain kernels / platforms have bugs regarding hugepages which can lead to problems:

Bug 131295 – Hugepages configured on kernel boot line causes x86_64 kernel boot to fail with OOM: Fixed in RHEL3: kernel-2.4.21-40.EL

Bug 248954 – Oracle ASM DBWR process goes into 100% CPU spin when using hugepages on ia64 (Fixed in kernel-2.6.9-78.EL.ia64.rpm available as update for RHEL4U7)

RHSA-2008:1017-14: on the Itanium® architecture, setting the “vm.nr_hugepages” sysctl parameter caused a kernel stack overflow resulting in a kernel panic, and possibly stack corruption. With this fix, setting vm.nr_hugepages works correctly. Fixed with RHEL5 kernel-2.6.18-92.1.22.el5.ia64.rpm

RHSA-2008:1017-14: hugepages allow the Linux kernel to utilize the multiple page size capabilities of modern hardware architectures. In certain configurations, systems with large amounts of memory could fail to allocate most of this memory for hugepages even if it was free. This could result, for example, in database restart failures. Fixed with RHEL5 kernel-2.6.18-92.1.22.el5.ia64.rpm

Therefore, before enabling hugepages, I recommend to check with your OS Vendor Bug Database, test on a test system and apply recent OS upgrades first.