Thanks for the question, liu.
Asked: January 08, 2019 - 9:42 am UTC
Last updated: January 09, 2019 - 1:57 pm UTC
Version: 11.2.0.4
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env:
oracle 11.2.0.4 rac
10000M/s network
mount the nfs filesystem on /orabak as the destination of dumpfiles
when i am using the compression=all parameter to dump a 80G schema ,the nfs write speed is 10-20MB
when i am not using the compression=all parameter to dump a 80G schema,the nfs write speed is 300-400MB
anyone knows why?Is this normal?
thasks a lot!
and Chris said...
When you're compressing data you're giving the database more work to do. This can "reduce" write speed because it's spending more time doing something else. Compressing the data!
So instead of looking at write speed, see what Data Pump is actually doing. Trace the sessions and compare to see what's different.
See
https://blogs.oracle.com/sql/how-to-create-an-execution-plan#tkprof for details on how to trace and parse the trace file.