Imm op in Top 5 wait event

Hi,
I found the event: "imm op" in the top of the "top 5 wait event" , at the awr report (10204 version) .
Is it an idel event ? is related to the fact that the database is bening backedup at the same time (event Backup: sbtbackup ) ?
Is there somthing i can do to reduce it value ?
Thanks
Top 5 Timed Events                                         Avg %Total
~~~~~~~~~~~~~~~~~~                                        wait   Call
Event                                 Waits    Time (s)   (ms)   Time Wait Class
imm op                                5,936       5,879    990   68.8      Other
Backup: sbtbackup                         8       5,752 ######   67.3 Administra
db file scattered read              200,642       3,335     17   39.0   User I/O
CPU time                                          3,177          37.2
log file parallel write             150,271       1,822     12   21.3 System I/O
          -------------------------------------------------------------

Hi Werner,
BACKUP_TAPE_IO_SLAVES is set to TRUE in the case of a RMAN backup if dedicated I/O slave processes are to copy backup write processes to tape and not the Oracle shadow processes. In this case, "imm op" waits only affect the backup runtime, but not the live system.My init.ora parameter are as followed:
backup_tape_io_slaves TRUE
dbwr_io_slaves 0
db_writer_processes 1
I dont know the reason why backup_tape_io_slaves is set to TRUE.
Would you suggest me to set it to FALSE and test it again ?
Thanks
End value
Parameter Name                Begin value                       (if different)
aq_tm_processes               0
background_dump_dest          C:\ORACLE\ADMIN\XXX\BDUMP
backup_tape_io_slaves         TRUE
compatible                    10.2.0
control_files                 D:\ORADATA\XXX\CONTROL01.CTL, D:
core_dump_dest                C:\ORACLE\ADMIN\XXX\CDUMP
db_block_size                 8192
db_cache_size                 8388608
db_domain
db_file_multiblock_read_count 16
db_name                       xxxx
db_recovery_file_dest         T:\oradata\XXX\archive
db_recovery_file_dest_size    1073741824
dispatchers                   (PROTOCOL=TCP) (SERVICE=XXXXDB)
fast_start_mttr_target        300
instance_name                 xxxx
java_pool_size                0
job_queue_processes           3
large_pool_size               0
local_listener                LISTENER_xxxx
log_archive_dest_1            LOCATION=T:\oradata\XXX\archive
log_archive_format            %t_%r_%s.dbf
max_dump_file_size            UNLIMITED
nls_length_semantics          BYTE
open_cursors                  1200
processes                     150
query_rewrite_enabled         FALSE
remote_login_passwordfile     EXCLUSIVE
resource_limit                TRUE
resource_manager_plan
session_cached_cursors        300
session_max_open_files        20
sga_target                    838860800
shared_pool_size              0
sort_area_size                524288
star_transformation_enabled   FALSE
streams_pool_size             50331648
timed_statistics              TRUE
undo_management               AUTO
undo_retention                3600
undo_tablespace               UNDOTBS1
user_dump_dest                C:\ORACLE\ADMIN\XXX\UDUMP
          -------------------------------------------------------------

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986330 wrote:
Hi,
I hope I'm asking this question in right place.
I need a script and its output should give me the top 5 wait events in last 1 hour for an instance.
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hi,
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hi,
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With Regards
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"control file parallel write" event occurs while the session is writing physical blocks to all control files.
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Top Wait Events

hi gurus,
3 node rac 10.2.0.4 serving a packaged application.
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Time(s)=1,950
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% Total Call Time=45.3
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Time(s)= 1,396
Avg Wait(ms)=0
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Time(s)= 719
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% Total Call Time=18.2
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if that's the case, is there a way to find optimum value for db_file_multiblock_read_count?
or any other findings please?
experts, appreciate your valuable help
thanks in advance,
charles

user570138 wrote:
there are queries going for the full table scan with outer joins (milliion of records). those are the same sqls at the top of "sql order by cluster time"in awr with high CPU utilization.
any way to fine tune the instance to reduce the "gc cr multi block request"
apart from changing the code as the code belongs to a package based application please?
Do you have a performance problem ?
You are doing some large tablescans; these are (probably) the root cause of the gc cr multiblock read, the db file scattered reads, and the CPU, but if the queries are necessary and the execution paths are the best that can be done then maybe you just have to recognise that the resource you're using is reasonable for the queries you have to run.
Otherwise
<ul>
(a) can you find a more efficient access path for any of these queries
(b) can you make sure that all these queries run on the same node so that you get some benefit from node-affinity (possibly the object(s) will be remasted to that single node) and reduce the interconnect traffic.
</ul>
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
http://www.jlcomp.demon.co.uk
To post code, statspack/AWR report, execution plans or trace files, start and end the section with the tag {noformat}{noformat} (lowercase, curly brackets, no spaces) so that the text appears in fixed format.
"Science is more than a body of knowledge; it is a way of thinking"
Carl Sagan

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Hi!
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~~~~~~~~~~~~~~~~~~ wait Call
Event Waits Time (s) (ms) Time Wait Class
CPU time 932 71.3
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The manual page isn't very helpful:
http://download.oracle.com/docs/cd/E11882_01/server.112/e17110/waitevents003.htm#insertedID40
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sb92075 wrote:
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--By Jnathan Kehayias
SELECT TOP 10
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/ SUM(wait_time_ms) OVER ( ) AS percent_total_resource_waits
FROM sys.dm_os_wait_stats
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AND wait_type NOT IN -- filter out additional irrelevant waits
( 'SLEEP_TASK', 'BROKER_TASK_STOP', 'BROKER_TO_FLUSH',
'SQLTRACE_BUFFER_FLUSH','CLR_AUTO_EVENT', 'CLR_MANUAL_EVENT',
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Please mark this reply as the answer or vote as helpful, as appropriate, to make it useful for other readers

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DB version:11.1.0.7.0
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SQL> SELECT INDEX_NAME,INDEX_TYPE,UNIQUENESS FROM DBA_INDEXES WHERE TABLE_NAME='DATA_DATA';
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VIDX BITMAP NONUNIQUEYou have bitmap indexes here on a table being inserted into. Bitmap Indexes are another source of lock(and deadlock) in OLTP application. You said that the SQLloader was the unique active program but may be you are also triggering another procedure after the load. Procedure in which you might be using also automomous transactions and so on...
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10g is a marketing label not a version number.
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Interpret DB CPUwait event (top 5 wait event AWR)

Hi,
Can anyone tell me how to read the table below especially the "DB CPU" section,
Is it right to say that 41.71% of time was consumed waiting for CPU?? this is urgent
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db file sequential read      300,835      1,483           5           58.42           User I/O
DB CPU                     1,059                     41.71
reliable message           9,499           18           2           0.71           Other
PX Deq: Slave Session Stats      6,506           11           2           0.43           Other
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user589420 wrote:
Hi,
Can anyone tell me how to read the table below especially the "DB CPU" section,
Is it right to say that 41.71% of time was consumed waiting for CPU?? this is urgent
Event                           Waits Time(s) Avg wait (ms) % DB time Wait Class
db file sequential read       300,835    1,483              5      58.42 User I/O
DB CPU                                   1,059                     41.71
reliable message                9,499       18              2       0.71 Other
PX Deq: Slave Session Stats     6,506       11              2       0.43 Other
gc cr grant 2-way              26,218        6              0       0.25 Cluster
When posting information to the forum that includes critical spaces, like the above, use a { code } tag (without spaces) before and after the information.
I do not understand why this question is an urgent problem.
It is incorrect to state that 41.71% of the time was consumed waiting for the CPU. When an Oracle process is running on the CPU, it is officially not waiting. It causes a bit of confusion having the CPU time consumed listed among the top 5 wait events, but as long as you understand why it is in the top 5 list, it almost makes sense for it to be included.
The DB CPU statistic is listed as 1,059 seconds. If the duration of this report is 1 hour, that is 3,600 seconds of total time. If there is a single CPU in the server, there are 3,600 CPU seconds available in the time period, indicating that the server's CPU on average was 29.4% busy. If there were 12 CPUs in the server, there were 43,200 CPU seconds available in the time period, indicating that on average the CPUs were 2.5% busy. Does this mean that there was a problem, or was this OK, or is there not enough information? Just because on average the CPUs are not busy, that does not mean that there were not periods of intense CPU competion, where in fact there was a temporary shortage of available CPU time for processing.
The DB Time statistic is supposed to be an indication of work performed by the instance on behalf of the user sessions. It is the accumulation of CPU time consumed by foreground sessions plus the accumulated sum of all non-idle wait events consumed by foreground sessions. Blog articles that might be of interest to you:
http://hoopercharles.wordpress.com/2010/01/13/working-with-oracle-time-model-data/
http://hoopercharles.wordpress.com/2010/02/05/faulty-quotes-6-cpu-utilization/
Charles Hooper
Co-author of "Expert Oracle Practices: Oracle Database Administration from the Oak Table"
http://hoopercharles.wordpress.com/
IT Manager/Oracle DBA
K&M Machine-Fabricating, Inc.

( name-service call wait   ) event   is amoung the top 5 wait events

10.2.0.3 2node- RAC
When I check the wait event in the active session wait event the sessions can be see that they are blocked by the LMON process. The wait event appears only on one node.
It is very hard to find information on the net or on the metalink.
How could I overcome this wait event ?
select program, type from v$session
     where sid in
     (select blocking_session from v$active_session_history
               where event like 'name-service%'
     and rownum < 1000 )
oracle@dbokyanus1 (LMON) , BACKGROUND
Top 5 Timed Events Avg %Total
~~~~~~~~~~~~~~~~~~ wait Call
Event Waits Time (s) (ms) Time
db file sequential read 4,331,507 15,218 *4* *31.2*
CPU time *8* *17.5*
log file sync 1,462,968 5,513 *4* *11.3*
name-service call wait 72,058 4,545 *63* *9.3*
SQL*Net message from dblink 4,197 4,047 *964* *8.3*

oceanic-815 wrote:
10.2.0.3 2node- RAC
When I check the wait event in the active session wait event the sessions can be see that they are blocked by the LMON process. The wait event appears only on one node.
It is very hard to find information on the net or on the metalink.
If I use Google to find information about this
I ran into this page.
There is indeed not much to find about this wait-event, other than there is probably some sort of network communication problem between the two nodes.
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Top 5 wait events in AWR Repprt

Hi,
The following is top 5 wait event in my AWR reports...
Whenever I take reports this are always top 5 events
Top 5 Timed Events
=============================================================================================================
Event
CPU time
Waits               4,717
% Total Call Time     62.0
log file sync
Waits                64,963
Time(s)               1,362
Avg Wait(ms)          21
% Total Call Time     17.9
Wait Class          Commit
log file parallel write
Waits               63,485
Time(s)               1,004
Avg Wait(ms)          16
% Total Call Time     13.2
Wait Class          System I/O
enq: TX - row lock contention
Waits               348
Time(s)               984
Avg Wait(ms)          2,828
% Total Call Time     12.9
Wait Class          Application
db file parallel write
Waits               29,305
Time(s)               561
Avg Wait(ms)          19
% Total Call Time     7.4
Wait Class          System I/O
------------------------------------------------------------------------------------------------------------

Start with Performance Tuning Guide
10.2.3 Table of Wait Events and Potential Causes

Imm op in Top 5 wait event

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