Hitachi 9900 Series, 9960 manual Hitachi Data Systems, Test Results

Hitachi Data Systems

Bottleneck-free performance with the Lightning 9900™ Series.

Internal Switching Overcomes the Limitations of Shared Bus Architectures

It can be seen from Figure 24 that a reduction occurs in the OLTP performance for the shared bus architecture of the 7700E system. This occurs at Point 1, when the DSS application begins at about 45 minutes into the test. It depicts the effect that the DSS application (full table scans) has on the OLTP workload due to the fact that both applications compete for bus bandwidth. In the Lightning 9900™ Series system, with its Hi-Star™architecture, however, each workload essentially has its own internally routed paths. This means that the main reason for performance decline for the OLTP application i.e., bus contention, does not occur when the DSS application starts. Although there may be some contention at the cache, there are 16 simultaneous operations concurrently happening at the cache. This far exceeds the demands of most application requirements, which can be measured with the limited multiple shared bus architectures on the market today.

Test Results

The DSS application starts performing full table scans while the OLTP application has been running by itself for approximately 45 minutes. The 9960’s OLTP application started at a Transaction Per Minute (TPM) rate of about 2350 and sustained this rate during the start of the DSS application and throughout the DSS application’s run. The 9960’s DSS application started with a transfer rate of about 220MB/sec or over 2.3 million rows per second. There was no reduction in TPM.

In other words, the DSS application did NOT affect the 9960’s OLTP application performance as it does on the shared bus controller system.

Also when the 9960’s OLTP application completes the DSS application’s transfer rate is maintained at 220MB/sec or over 2.3 million rows per second. Again, there is no reduction in MB/sec or rows per second with the Lightning 9900™ Series.

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