Summary

Dell Technologies newest RAID iteration, PERC11, has undergone significant change - most notably the inclusion of hardware RAID support for NVMe drives. To better understand the benefits that this will bring, various metrics were tested, including NVMe IOPS, disk bandwidth and latency. This DfD compares NVMe performance readings of the next-generation Dell EMC PowerEdge R650 server, powered by pre-production 3rd Generation Intel® Xeon® Scalable processors, to the prior-generation PowerEdge R640 server, powered by 2nd Generation Intel® Xeon® Scalable processors.

Introduction

With support for NVMe hardware RAID now available on the PERC11 H755N front, H755MX and H755 adapter form factors, we were eager to quanitfy how big of a performance boost next-generation PowerEdge servers with hardware RAID would obtain. Dell Technologies commissioned Principled Technologies to execute various studies that would compare the NVMe Input/Output Per Second (IOPS), disk bandwidth and latency readings of next-geneation PowerEdge servers (15G) with NVMe hardware RAID support against prior-generation PowerEdge servers (14G) without NVMe hardware RAID support.

Test Setup

Two servers were used for this study. The first was a PowerEdge R650 server populated with two 3rd Gen Intel® Xeon® Scalable processors, 1024GB of memory, 3.2TB of NVMe storage and a Dell PERC H755N storage controller. The second was a PowerEdge R640 server populated with two 2nd Gen Intel® Xeon® Gold Scalable processors, 128GB of memory, 1.9TB of SSD storage and a Dell PERC H730P Mini storage controller.

A tool called Flexible Input/Output (FIO) tester was used to create the I/O workloads used in testing. FIO invokes the production of threads or processes to do an I/O action as specified by the user. This test was chosen specifically because it injects the smallest system overhead of all the I/O benchmark tools we use. This in turn allows it to deliver enough data to the storage subsystem to reach 100% utilization. With the tool, five workloads were run at varied thread counts and queue depths on RAID 10, RAID 6, and RAID 5 levels of the Dell EMC PowerEdge R650 server with PERC H755n RAID controller and NVMe drives and the Dell EMC PowerEdge R640 server with a PERC H730P Mini controller and SATA SSD drives.

Read-heavy workloads indicate how quickly the servers can retrieve information from their disks, while write-heavy workloads indicate how quickly the servers can commit or save data to the disk. Additionally, random and sequential in the workload descriptions refer to the access patterns for reading or writing data. Random accesses require the server to pull data from multiple disks in a non-sequential fashion (i.e., visiting multiple websites), while sequential accesses require the server to pull data from a single continuous stream (i.e., streaming a video).

Performance Comparisons

IOPS

IOPS indicates the level of user requests that a server can handle. Based on the IOPS output seen during testing, upgrading from the prior-generation Dell EMC PowerEdge R640 server to the latest-generation Dell EMC PowerEdge R650 server could deliver performance gains for I/O-intensive applications. In all three RAID configurations tested, the PowerEdge R650 with NVMe SSDs delivered significantly more IOPS than the prior-generation server. Figures 1, 2 and 3 show how many average IOPS each configuration handled during testing:

Figure 1: IOPS comparison for RAID 10 configurations

Figure 2: IOPS comparison for RAID 6 configurations

Figure 3: IOPS comparison for RAID 5 configurations

Disk Bandwidth

Disk bandwidth indicates the volume of data a system can read or write. A server with high disk bandwidth can process more data for large data requests, such as streaming video or big data applications. At all three RAID levels, the latest-generation Dell EMC PowerEdge R650 server with NVMe storage transferred significantly more MB per second than the prior-generation server. Figure 4 shows the disk bandwidth that each of the two servers supported for each RAID level:

Figure 4: Disk bandwidth comparison for RAID 10, 6 and 5 configurations

Latency

Latency indicates how quickly the system can respond to a request for an I/O operation. Longer latency can impact application responsiveness and could contribute to a negative user experience. In addition to greater disk bandwidth, the Dell EMC PowerEdge R650 server delivered lower latency at each of the three RAID levels than the prior-generation server. Figure 5 shows the latency that each server delivered while running one workload at each RAID level.

 
Figure 5: Latency comparison for RAID 10, 6 and 5 configurations

Conclusion

The next-generation PowerEdge R650 server with NVMe HW RAID support increased IOPS by up to 15.7x, disk bandwidth by up to 15.5x, and decreased latency by up to 93%. With the inclusion of NVMe HW RAID support on Dell Technologies’ new PERC11 controllers, now is a great time for PowerEdge customers to migrate their storage medium over to NVMe drives and yield the higher-performance that comes with it!

For more details, please read the full PT report Accelerate I/O with NVMe drives on the New PowerEdge R650 server