Fusion-io ioDrive 640GB Solid State Storage Device

Designed around a revolutionary silicon-based storage architecture known as ioMemory, the ioDrive is the world’s most advanced NAND clustering technology with performance comparable to DRAM and storage capacity on par with today's hard disks — giving you the power to improve both memory capacity and storage performance by up to one thousand times. The ioDrive dramatically increases performance such that every server can easily contain the I/O performance of the world's fastest enterprise SAN.

• Capable of over 120,000 random read/write IOPS
• Allows for less than 50 microsecond access latency
• Enables terabytes of Virtual Memory with near DRAM speeds
• Eliminates service interrupts due to I/O contention
• Save or resume virtual machine states in seconds

Performance

The ioDrive demonstrated its highest sustained IOPS performance in read traffic with a rate of over 140,000 IOPS in file system tests at a 1KB request size and an impressive rate of just over 180,000 IOPS in raw device testing at a 512b request size. Interestingly, the random read performance surpassed the sequential performance in the file system tests. The throughput rate of the ioDrive was measured at a highest sustained rate of about 770MB/s in read traffic in both file system and raw device tests. Random write tests on file systems yielded nearly 120,000 IOPS and a throughput rate of approximately 650MB/s. The performance capabilities of the ioDrive solid state target present a substantial performance benefit in both IOPS and throughput over conventional hard drives in enterprise systems.

Device Longevity

The majority of this paper has concentrated on NAND flash in an enterprise-class storage device, and how to leverage its strengths while overcoming its weaknesses. NAND flash, however, is only part of a Fusion-io’s storage device. The flash chips reside on a PCIe adapter card that has a number of other parts as well, all of which are susceptible to failure. The life of a NAND flash storage device can be estimated by examining the failure rate of its component parts. Wear-out is generally a function of having lost enough storage cells that both capacity and reliability drop below acceptable thresholds. This can be assessed by evaluating and keeping a record of the amount of errors detected at each physical location. NAND flash wears out at a predictable rate.

Effective use of wear-leveling strategies employed by Fusion-io can significantly improve the life expectancy of its drives. Please note that the formulas are applied to both MLC and SLC NAND-based non-volatile memory technologies. Single-Level Cell (SLC) NAND and Multi Level Cell (MLC) NAND offer capabilities that serve two very different types of applications – respectively, those requiring high performance at an attractive cost-per-bit and those seeking even higher performance over time, that are less cost-sensitive

NAND Flash

Flash memory chips are a non-volatile storage medium (i.e., they can retain their information even in the absence of power). The most common types of flash chips are silicon-based NOR and NAND, named after the types of logic gates used in their design. NAND flash, introduced in 1989, has become the most commonly used type of flash chip, due to its quicker write speed. Flash memory continues to grow in popularity as its price steadily declines, its storage capacity increases, and its physical size continues to decrease.

In Fusion-io’s storage devices, NAND flash chips are stacked several at a time (to increase density), operated in parallel (to increase throughput) and mounted on a printed circuit board (PCB) that plugs into a PCI-Express (PCIe) slot on the server or in the CPU. The flash media is integrated with the controller onto a single PCI-Express card. NAND flash, as a storage medium, offers a number of benefits in comparison to rotating magnetic storage devices (aka HDD, Hard Disk Drives). NAND flash has no moving parts and is therefore significantly less prone to shock or movement disturbance. It is a high speed solution in both latency and throughput. Temperature and humidity resistance mean that it can operate in a number of different environments. Finally, NAND flash consumes significantly less power than rotating magnetic storage devices, particularly when you take into account secondary power requirements for device cooling.

Data Integrity

Data integrity means having a high degree of confidence that what you put into a storage system is exactly what you get out when you request that data and it is the most important function of a storage system. While being moved from a computer’s RAM or CPU to the Fusion-io device, several proven industry-standard approaches are used to ensure data integrity. The CPU, chipset, and RAM use SECDED (Single Error Correct Double Error Detect) or chipkill (method for on-the-fly replacement of a failed chip) to ensure accuracy. Once data is written to the storage medium, it is again checked for accuracy. When data is read from the storage medium, error correction techniques are again employed to ensure that the data being retrieved is correct. The device can correct a substantial portion of the data being read.

NAND’s reputation for unreliability is based on studies that show potential data loss without utilizing error correction – or less correction than that employed by the Fusion-io device. Using the methods described here, Fusion-io devices can produce results that exceed target error probability by about four times. Fusion-io’s devices also use a patent-pending approach when writing data, which allows the data’s path to be reconstructed from information generated during the write process.

Driving for Energy Reduction

Fusion-io has brought to the market a non-volatile solid state storage device based on NAND called the ioDrive. The ioDrive is unique in that it offers the performance of a SAN in one compact storage device. Better still, it does so while consuming a minuscule amount of power. In fact, the ioDrive equals the performance of 600 parallel HDDs in a SAN (comprising the HDDs, the redundant power systems; redundant network equipment; HBAs; and more) but only requires the energy of just one of those hard disk drives. This means eliminating around 10,000 Watts of power with the use of a single ioDrive. This is analogous to impact of Compact Florescent Lights (CFLs) versus incandescent bulbs. “They (CFLs) can use less than one-third the electricity of incandescent bulbs of equivalent brightness and last up to nine years…Top-end 24-watt bulbs promise brightness equivalent to that of a 150-watt incandescent. With this superior storage technology, not only can the performance and throughput of the data center increase but IT managers can reduce the amount of memory installed in a server, and collapse entire storage tiers, thus dramatically reducing, by orders of magnitude, overall energy consumption.

Fusion-io customers have experienced dramatic improvement in application performance when utilizing the power of the ioDrive. In one case, a customer was able to achieve improved MySQL application performance after installing two 160GB ioDrives into a server, which permitted them to disconnect their 100-hard-disk storage array, shut down 3 of the 4 Intel processors, and reduce the main memory from 64GB to 24GB. The number of application transactions per second increased to 11,000 per second from 9000 per second.

Besides the obvious reduction in costs (including software licenses), IT hardware power consumption was reduced by more than 90% for equivalent application performance. Processor utilization dramatically improved resulting in an increase in the performance per Watt because the ioDrive was able to deliver data at a substantially faster rate. But more importantly, the ioDrive did so at a fraction of the power and without the large typical data center infrastructure. The elimination of the power-hungry IT equipment reduces the data center’s demand on energy while maintaining or increasing application performance.