Troubleshooting

Improving Oracle OLTP database performance with Dell Fluid Cache for DAS

Executive summary

With increasing capacity and more affordable prices, the very fast, low-latency, flash-based Peripheral

Component Interconnect Express (PCIe) Solid State Devices (SSDs) are finding a place in modern

enterprise data centers. As a result, many enterprise hardware companies have begun to integrate and

offer these PCIe SSDs in their commodity servers. One of the ways to leverage these server-side PCIe

SSDs is by using a host-based caching software that can cache the application workloads and thereby

accelerate performance. This method can provide an excellent solution to overcome the performance

bottleneck of an existing traditional spinning disk-based storage solution. Alternatively, this method

can provide an excellent solution for new environments looking for very low-latency application

performance. Dell Fluid Cache for DAS (Fluid Cache) is a new host-based caching solution that

combines the Fluid Cache for DAS software with ultra-high speed Dell PowerEdge

Express Flash PCIe

SSDs to create a high-performance cache within the server itself.

This paper provides a reference architecture of the Fluid Cache based storage solution and

demonstrates how the performance of an online transaction processing (OLTP) database can be

accelerated using this solution. The study compares the performance of the Fluid Cache based storage

solution to a traditional hard disk drive (HDD)-based storage solution used as the baseline

configuration.

The key performance improvement findings from this study show that the Fluid Cache based solution

compared to the baseline configuration

 Delivers approximately 60% more transactions per second (TPS)

 Delivers approximately 95% improvement in average response time (ART) at 3100 user load

 Supports approximately 34% more users while delivering two seconds or less ART

Introduction

In a typical OLTP database environment the data blocks that are read or are written to are small in size

and are distributed at random places on the storage disks. Due to this nature of an OLTP environment,

its performance in a traditional spinning HDD-based storage is greatly dependent on the speed at which

the disk head can seek the data blocks to read or write to. However, the speed or the movement of the

disk head is mechanically restricted; therefore, each storage disk can deliver limited input/output

operations per second (IOPS) performance. So in order to keep up with the increased demand for IOPS

performance, the number of spinning disks must be increased. However, beyond a certain point, adding

additional disks will increase capacity but not performance, since the storage controller has reached its

maximum processing capabilities.

With very fast enterprise-class PCIe SSDs now being integrated and offered in standard commodity-

based servers can help to solve this problem. One of the ways to leverage these server-side PCIe SSDs is

to make use of a host-based caching software that can use these PCIe SSDs as a caching device and

thereby accelerate the database performance. However, a lot of the host-based caching software

currently in the market only support caching of the read data. As a result, the database is still

dependent on the backend spinning disks to write either the new or the modified dirty data to, and this

limits the overall performance. Dell Fluid Cache for DAS (Fluid Cache), a new host caching software,

overcomes this limitation by allowing caching of both read and write I/Os on to the local PCIe SSDs.