Authored by Naveen Iyengar, Dell Database Solutions Engineer
Dell’s Fluid Cache for Direct Attached Storage (DAS) software is a host caching software that uses Dell PowerEdge Express Flash PCIe SSDs installed on supported Dell systems to provide a read and write cache pool. The cache pool is used to accelerate response times with significant improvements in input/output operations per second (IOPS). On paper, this feature should definitely benefit an online transaction processing (OLTP) database environment and hence we conducted a study in the Dell solutions lab to evaluate the same.
Figure 1 shows the test bed that was setup to conduct the study. Dell PowerEdge R720 was setup as a single node database server. The server is directly-attached to four fully populated Dell PowerVault MD1220 storage arrays using the Dell PERC H810 external RAID controller. Eight RAID10 virtual disks (VDs) were used for datafiles and four RAID5 VDs were used for backup logs. Fluid Cache cache pool was setup using two 350GB Dell Express Flash PCIe SSDs and the VDs used for the datafiles were enabled for caching in write-back mode.
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Figure 1 Dell Fluid Cache for DAS architecture with OLTP database
Dell Quest Benchmark Factory (BMF) was used as the standard benchmarking tool. It was used to create a TPC-C database schema and to generate the OLTP workload. The OLTP benchmark was first run on a baseline configuration that comprised of the same hardware and software configuration that was used for the Fluid Cache test bed, except that it did not use the PCIe SSDs and the Fluid Cache software. Later the same OLTP benchmark was run on the Fluid Cache test bed. Two seconds was used as the maximum accepted average response time (ART) and any performance result past that ART was discarded.
The graph in Figure 2 plots the comparative transactions per second (TPS) performance of the baseline configuration (BC) and the Dell Fluid Cache (DFC) test beds.
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Figure 2 Baseline configuration vs. Dell Fluid Cache TPS performance
The graph in Figure 3 plots the comparative average response time (ART) performance of the baseline configuration (BC) and the Dell Fluid Cache (DFC) test beds.
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Figure 3 Baseline configuration vs. Dell Fluid Cache ART performance
Below is a summary of the performance improvement of the OLTP database with Fluid Cache over the baseline configuration based on the results captured:
· Fluid Cache delivered approximately 60% more TPS compared to the baseline configuration
· Fluid Cache delivered approximately 95% better average response time over the baseline at 3100 user load
· Fluid Cache delivered approximately 34% more user load compared to the baseline.
Based on the results we can conclude that OLTP users looking for a boost in TPS performance while keeping a very low latency can greatly benefit with Dell’s Fluid Cache for DAS caching solution.
Be on the lookout for a detailed technical whitepaper about the same study coming out soon on www.dell.com
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