Review: Intel's X25-E SSD runs circles around rival drives

Computerworld - There's something special about installing what is arguably one of the fastest, most sophisticated solid-state disk (SSD) drives in your average Dell laptop. It's a little like stuffing a big-block V8 into a Chevy Chevette -- you get amazing performance, but no matter how hard you try, you can't justify the cash you just shelled out in order to go really fast.

Intel Corp.'s X25-E Extreme SATA SSD (model SSDSA2SH064G1GC) is an enterprise-class drive meant for use in data centers, not run-of-the-mill laptops. But the drive has become one of the better known SSDs because Intel was early to the market with it and because of its sophisticated architecture, screaming performance and stalwart reliability.

My goal was to see if that reputation is deserved, especially given the interest in all things SSD among early technology adopters.

For my tests, I used a Dell Latitude D830 with a 2.4-GHz Intel Core 2 Duo processor running Windows XP Professional SP2. I wanted to test the drive to see how its use would affect the laptop's battery life, so I used MobileMark 2007, a BAPCo benchmark application that simulates the typical use of common applications such as PowerPoint, Outlook and Excel. For I/O performance tests, I used both ATTO Technology's ATTO Disk Benchmark v2.34 and Simpli Software's HD Tach v3.0.4 benchmarking utilities.

The guts

Unlike Intel's consumer SSD, the X25-M, the X25-E is built with single-level cell (SLC) NAND flash chips, which store one bit per cell, unlike multilevel cell (MLC) flash, which stores two or more bits per cell. While MLC flash offers greater capacity natively, SLC delivers better performance, reliability and longevity. But it also costs: A 64GB X25-E goes for more than $800 on Pricegrabber.com. In comparison, Intel's 80GB X25-M will run you around $360.

But if you need unerring reliability and longevity, an SLC drive is the one you want. It has a more sophisticated controller and can handle about 100,000 write/erase cycles -- about 10 times the number of cycles the best MLC-based drives on the market can handle.

Intel's X25-E solid state disk drive.

The X25-E gets its native speed from the SLC memory and from the fact that it interleaves NAND flash chips and uses 10 parallel channels to those chips. Intel is not alone in the use of a multichannel architecture, but it was among the very first to hit the market with it. The X25-E also relies on a proprietary controller with firmware that performs native command queuing and advanced wear-leveling and write amplification reduction operations.

Wear-leveling and write amplification algorithms are common in today's midrange and enterprise-class SSDs. Wear-leveling algorithms are used to more evenly distribute data across flash memory so that no single section wears out faster than any other, prolonging the life of whole drive. The controller in wear-leveling operations keeps a record of where data is set down on the drive as it's relocated from one portion to another.