Serial Storage Wire

6Gb/s SAS delivers over 1 Million IOPs!

By Robin Wagner, Senior Director, Marketing,
LSI

Introduction
In a 6Gb/s SAS technology demonstration at the Spring 2009 Storage Networking World Conference in Orlando, Florida, Serial Attached SCSI (SAS), in combination with enterprise drive enhancements and improved chip set architectures, SAS technology was able to deliver over one million I/Os per second operation (IOPs) from a single server. The demonstration utilized standard building blocks (described below) and demonstrated the new level of performance of the underlying 6Gb/s SAS technology. This was an important milestone for SAS technology and paves the way for increased Direct Attach Storage (DAS) adoption in data center environments.

Figure 1. Storage Networking World 2009 Performance Results

What is the significance of the milestone achievement?
As a frame of reference for small block IOPs performance, Ultra320 SCSI was able to perform 100,000 IOPs in 2002. Subsequently in 2006, 3Gb/s SAS delivered an impressive 500,000 IOPs, in its first generation.

Figure 2. Ultra320 SCSI performs 100,000 IOPs in 2002

Demo Specifics

System: Single Socket/Multi-core Workstation Platform
Hard Disk Drives: Twelve 6Gb/s SAS Hard Drives
SAS Controllers: Three 6Gb/s SAS Host Bus Adapters (HBAs)
Operating System: Windows OS
Workload: 1K Sequential Block I/Os

The demo platform was a single socket processor-based workstation platform which fits into a small desktop chassis. The system is based on the latest CPU technology and chipsets designed for multi-core processor performance, and delivers greatly improved shared memory performance when compared to the previous generation CPU/chipset combinations. The demonstration was based on a single socket, 4-core CPU. Since each core is hyper-threaded it looks like an 8-CPU system to the OS. Using a high percentage of available CPU utilization, a remarkable 1.1 million IOPs was achieved with this configuration. The smallest one-socket system available was selected in order to demonstrate that ultra-high performance is fully achievable on modest server hardware.

The system was configured using twelve 6Gb/s SAS HDDs or 4 disks per SAS controller, requiring only 50% of the available SAS ports on the selected SAS adapters. Over one million IOPs was actually achievable with as few as nine disks, however, twelve drives were used to push the results up to the CPU saturation point. Twelve disks is an exceptionally low number for attaining this class of performance. Each disk used in this demo delivers in excess of 200,000 IOPs from its cache, which is a significant increase over the previous generation enterprise drives. While rotating disks can deliver this throughput performance using sequential I/Os, Solid State Disks (SSDs) will soon achieve similar performance levels with small-block random I/O workloads as well. Because 6Gb/s SAS delivers this category of performance using a very small number of drives, it accentuates the underlying capabilities of the SAS architecture and delivers on the promise of supporting very high-speed, low latency devices.

Each of the SAS HBAs is capable of more than 400,000 IOPs in systems supporting the PCIe 2.0 system bus. Therefore, this new milestone in performance required three 6Gb/s SAS HBAs. Expect to see even greater levels of system performance in subsequent product generations.

Figure 3. 6Gb/s SAS-configured System performs at 1.1 Million IOPs

This demo was staged using a standard Windows operating system (OS) with no special optimization required, further validating proven Windows OS operating on the latest high performance hardware platforms. Average software latency, per I/O, was less than one microsecond for this set-up which was an important element in achieving these performance results.

Why is IOPs performance important to end users?
Many emerging applications will leverage these investments in 6Gb/s SAS and exploit this level of IO performance. One example is Data Mining where utilization of this technology will provide users with fast access to content. Another example is the Mega Data Center or Server Farms where many drives are used to redundantly store massive quantities of tiered data. The high IOPs performance level can be shared by large numbers of host processors, especially in clustered or virtualized server environments. This new performance level, combined with other second generation SAS features such as standardized zoning and self-configuring expanders AND excellent price/performance, makes 6Gb/s SAS an ideal technology solution for data centers and other demanding server application environments.