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Oracle Tips by Burleson |
ATA Configurations
The ATA array was tested for the following configurations:
- nologging and noarchive base run
- nologging and noarchive
- Logs and temp files on SSD
- Data on SSD full buffer memory (1 gigabyte)
- Data on SSD half buffer memory (500 megabytes)
The percentage difference between SSD and SATA are so large it
does not make sense to even report them; however, the total elapsed
times, adding in a base of 1,440 minutes per each non-complete query
for the SCSI, show a factor of 179 times difference between the SSD
and ATA results in favor of the SSD drives. The queries for the SSD
tests all completed, while several in the ATA tests were halted at
the 24 hour point.
In order to plot the results on a single plot, the vertical scale
had to be switched to logarithmic; therefore, the changes in query
time may only appear to be slight on the graph but may actually be
several tens of percentage points. The runs not involving the SSD
showed consistent results.
When the temp and undo tablespaces were moved to the SSD drives some
queries improved, while others got worse. When the data tablespace
was moved to SSD all query times were improved by an average of 100
percent. The reduction of db_cache_size by half with the data
tablespace on SSD actually show some improvements in performance on
queries number two, eight, 11, 13, and 13a, while the others
performed worse than the full memory levels. However, all of the
queries performed better with the data on the SSD than the ones on
100% ATA.
The above book excerpt is from:
Oracle RAC
& Grid Tuning with Solid State Disk
Expert Secrets for High Performance Clustered Grid Computing
ISBN:
0-9761573-5-7
Mike Ault, Donald K. Burleson
http://www.rampant-books.com/book_2005_2_rac_ssd_tuning.htm |
