Intel’s X25-E Versus The Fusion-io ioDrive

Flash Storage Taking Off

Progress in the storage segment has probably been more noticeable than in other market segments recently, except perhaps graphics. Faster processors are mainly noticeable if you have the applications able to take advantage of them, and advances on the platform side have been slight as well. But accelerated hard drives and storage products make a noticeable difference. Client PCs, such as desktops and notebooks, boot their operating systems and applications faster thanks to increased throughput, and servers can process more I/O operations per second with faster storage as well.

The recent developments in enterprise-class storage products are mind-boggling. We decided to look at the two most innovative products: Intel’s X25-E flash SSD for servers, and the ioDrive by Fusion-io. Both are based on flash memory and promise stellar performance compared to any type of mechanical hard drive, or even RAID arrays composed of them. Let’s find out which is the best server drive.

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The low-profile ioDrive can be installed into regular PCs or into 2U servers with an available x4 or wider PCI Express slot. You cannot yet boot from it, though, since it does not use a conventional mass storage interface. Clearly, this product isn’t really helpful on desktop PCs, but it impresses in servers, where a fast storage product and a high number of I/O operations per second are essential.

You have to use a utility called the IoManager to set your desired performance mode. You can either use the full capacity of 80 GB in the case of our test sample (Maximum Capacity mode), or switch to one of the performance enhancing modes. Improved Write Performance mode utilizes a sort of write distribution algorithm to accelerate writes, but it limits capacity to 40 GB. Finally there is a Maximum Write Performance mode, which further reduces capacity to 24 GB, while giving you even more write performance benefits. These benefits mostly affect I/O performance, but write throughput also gains somewhat—if you’re willing to give up the capacity, of course.

While Intel’s X25-M mainstream 2.5” flash SSD was extremely convincing, the X25-E is even better. It cannot provide more read throughput than its predecessor, and it is limited to 32/64 GB capacities until later this year, but its write transfer performance is at least twice as fast thanks to the faster SLC flash memory. The X25-M writes at less than 100 MB/s, while the X25-E reaches almost 170 MB/s. On the flip side, an X25-M is available at capacities of up to 160 GB.

The real advantages of the X25-E become obvious once you have it deal with I/O-intensive applications. It is simply much faster than any other flash SSD we have had in our storage test lab; it is capable of delivering I/O performance that puts it in a league of its own. A single X25-E flash SSD can provide the I/O performance of large and complex SAS RAID arrays based on 15,000 RPM hard drives. And it does this while consuming less than 2 watts of power, while such a RAID array will require 100 to 200 W.

Both sides of the circuit board are populated with SLC flash memory chips, but the top also holds Intel’s flash memory controller, including the Serial ATA interface. In addition, you can find a Samsung IC, which is used as a cache memory. As we could see on the X25-M as well as on the X25-E, the controller works extremely efficiently. Write amplification is not a major issue for the Intel drives, and performance turned out to be rather consistent when compared to other flash SSDs.

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System Hardware
Processor(s)	Intel Core 2 Duo E8500 (45nm, 3.16 GHz, 6MB L2 Cache)
Platform	Gigabyte P45T-Extreme, Rev 1.0Intel P45 Chipset, BIOS 1710
RAM	4x 1 GB DDR-1066 Crucial BL12864BA1608
System Hard Drive	Seagate Barracuda 7200.980 GB, 7,200 RPM, 8 MB Cache, SATA/300
Mass Storage Controller(s)	82801JIR ICH10 RAID (ICH10R)
Graphics Card	ATI Radeon 3850

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Benchmark Software
Performance Measurements	h2benchw 3.6
I/O Performance	IOMeter 2003.05.10, Fileserver-Benchmark, Webserver-Benchmark, Database-Benchmark, Workstation-Benchmark

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System Software And Drivers
OS	Microsoft Windows Server Standard x64 SP1
Platform Driver	Intel Chipset Installation Utility 9.0.0.1008
Graphics Driver	Radeon 8.11
Fusion-io Driver	Release 1.2.2.14

The database I/O benchmark results are quite interesting. Intel’s X25-E reaches 6,500 to 10,000 I/O operations per seconds at small command queue depths, but drops to a little more than 4,000 I/Os at deep command queues. The ioDrive is different. While it reaches 2.5x more performance than the X25-E at executing individual commands, it drops to a bit more than the Intel’s performance at longer command queues. Switching the ioDrive to one of the faster write modes, which results in reduced capacity, results in more than doubling I/O performance. In such a case, a RAID array of Intel X25-E SSDs could not catch up for the same cost of an ioDrive.

The fastest high-performance storage solution is the ioDrive by Fusion-io, which provides 80, 160, or 320 GB of storage capacity on a x4 PCI Express add-on card. It can be installed into any system that offers a suitable expansion slot, but you are limited to 64-bit operating systems because the product requires drivers. In addition, the ioDrive is not a conventional drive storage solution as we know them, since you cannot boot from it, and you cannot fit it into a small form factor system due to its add-on card design. Its price starts at around $3,000, and it provides the highest possible I/O performance at this price point; only RAM drives are capable of beating this—at much higher cost and smaller capacity.

However, Intel’s X25-E is not a loser. Our review revealed that it currently is the fastest standard drive for server environments. Its SATA/300 interface may not be suitable for all applications, but SAS controllers are capable of operating SATA drives as well. Capacities of the X25-E may not match those of the ioDrives or hard drives, but its capacity and performance per watt certainly do. At $500, the X25-E is affordable enough to create RAID arrays of five to six drives at the cost of an entry-level ioDrive.