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This section describes the Oracle performance validation tests that were done with PowerMax compression enabled and disabled. Oracle SLOB is used to generate OLTP workload in both tests and with the exact same configuration and runtime parameters. In the first test, SLOB data is loaded to a PowerMax storage group (SG) on which compression is disabled. In the second test, the SLOB data is loaded to a PowerMax SG on which compression is enabled. In both test cases, the Service Level of the storage group was set to Platinum, which is designed to provide high performance without limiting data reduction (such as the case with Diamond Service Level).
For more information about PowerMax Service Levels, see PowerMax Service Levels and Oracle.
To make SLOB data more realistic for compressibility tests, a SLOB Obfuscation feature is used, which makes the data semi-random. To enable Obfuscation of the data, you must run the following command before loading the SLOB data:
$ export OBFUSCATE_COLUMNS=TRUE
After the SLOB data load, the SG reported a Data Reduction Ratio (DRR) of 4.7:1, with about 1.2 TB of SLOB data loaded (scale of 20 GB x 64 users = 1,280 GB). SLOB is set to UPDATE_PCT=25 to generate about 25 percent data updates, which is commonly observed in OLTP databases.
The results are taken from an Oracle AWR report collected for each test, where IOPS are taken from the AWR IO Profile section for the database requests category. The read I/O response time is taken from the AWR Top 10 Foreground Events section for the db file sequential read category, which represents the read latency of database I/Os in microseconds (usec).
As shown in Figure 2, the performance differences between the two test cases are negligible. IOPS dropped by 2.5 percent when compression was enabled, while improving latency by 1 percent. However, this latency improvement can be attributed to the slight variation in database performance tests.
Although not shown in the graph, the data from Unisphere for the Oracle datafiles storage group shows that when PowerMax compression is enabled, the I/O read latency changes from 341 to 346 microseconds (<0.5 percent). In addition, the IOPS dropped from 208,138 to 206,879 (<1 percent).
The performance figures for when PowerMax compression is enabled and disabled are similar because the PowerMax compression engine is designed to identify and keep the hot data uncompressed to avoid overhead. The compression engine, together with PowerMax hardware compression modules that make compression and decompression of the data very fast, result in strong data reduction benefits with minimal impact to performance.