Re: datapump export incredibly slow
- From: David Fitzjarrell <oratune@xxxxxxxxx>
- To: "Chris.Stephens@xxxxxxx" <Chris.Stephens@xxxxxxx>, "'oracle-l@xxxxxxxxxxxxx'" <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 14 Feb 2014 14:10:45 -0800 (PST)
I have to ask why you're running PARALLEL=4 and only creating one dump file?
It may be that the parallel processes running for the export are waiting for a
coordinator to consolidate query results and also the parallel write processes
may get into a queue to write to the singleton dump file. Such actions could
very well result in the waits you're seeing where 'nothing' is being done.
Can you try using as many dump files as parallel processes (4)? Your parfile
list would then look like this:
SCHEMAS=xxxxxxx
CONTENT=ALL
DUMPFILE=xxxxxxx_full1.dmp, xxxxxxx_full2.dmp, xxxxxxx_full3.dmp,
xxxxxxx_full4.dmp
LOGFILE=xxxxxxxx_full.exp.log
CLUSTER=N
PARALLEL=4
COMPRESSION=ALL
FLASHBACK_TIME=SYSTIMESTAMP
EXCLUDE=STATISTICS
This might mitigate the issues you report.
David Fitzjarrell
Primary author, "Oracle Exadata Survival Guide"
On Friday, February 14, 2014 2:01 PM, "Stephens, Chris"
<Chris.Stephens@xxxxxxx> wrote:
11.2.0.4 RAC on Oracle Linux 6.
Right now I’m battling an unbelievably slow export but imports seem
unreasonably slow as well. This occurs in two different RAC environments. I
have a ticket open with Oracle but that’s not getting me anywhere quite.
I’m exporting with the following parameters:
SCHEMAS=xxxxxxx
CONTENT=ALL
DUMPFILE=xxxxxxx_full.dmp
LOGFILE=xxxxxxxx_full.exp.log
CLUSTER=N
PARALLEL=4
COMPRESSION=ALL
FLASHBACK_TIME=SYSTIMESTAMP
EXCLUDE=STATISTICS
It looks like the export does some work (lots of direct path reads) for a while
and then does nothing with tons of waits similar to:
*** 2014-02-14 14:51:25.924
WAIT #139990593434552: nam='wait for unread message on broadcast channel' ela=
1000810 channel context=93982405280 channel handle=94519841120 p3=0 obj#=803670
tim=1392411085924778
*** 2014-02-14 14:51:26.925
WAIT #139990593434552: nam='wait for unread message on broadcast channel' ela=
1000867 channel context=93982405280 channel handle=94519841120 p3=0 obj#=803670
tim=1392411086925789
EXEC
#139990593434552:c=2999,e=5009559,p=0,cr=4,cu=0,mis=0,r=0,dep=3,og=4,plh=0,tim=1392411086926186
ERROR #139990593434552:err=25228 tim=1392411086926229
CLOSE #139990593434552:c=0,e=4,dep=3,type=3,tim=1392411086926370
I’m guessing that error possibly indicates a bug?
The export is estimated to be ~80GB. I let it run for several hours this
morning and it was nowhere close to being done.
Anybody have any ideas or seen this before?
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