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Multiplexing Tests


Notes:

I did not have a striped disk configuration to test with, so I will demonstrate only the effect of multiplexing in a non-striped environment. Here we see three tests, using multiplexing levels of 4, 8 and 16. We see that the multiplexing level of 8 was best in my environment: a 5% reduction in elapsed time (see the previous “tape compression” test, elapsed time 8100, multiplexing level 1) and a 5% increase in bytes per second.

The following is supplied script v$backup_async_io.sql, which created the result shown in the slide:
select to_char(close_time, 'mm/dd hh:mi') as time, type,
maxopenfiles,
elapsed_time as et,effective_bytes_per_second as eb
from v$backup_async_io
where close_time > sysdate - (1/24 / 4) /* within last .25 hour */
and type = 'AGGREGATE'
/