Western Digital's WD RE (RAID Edition) series of drives--now in their 3rd generation--are 3.5 inch offerings designed especially for use in RAID systems. Currently served in 160GB - 750GB (RE2), 250 - 500 GB (RE3), and 500 GB - 1 TB (RE2-GP) capacities, these SATA drives are not intended or recommended for use in standard desktop implementations.

In many ways, the RE series of drives are similar to their WD Caviar SE cousins; they spin at 7200 RPM and offer an average read seek time of 8.9 ms. The cache is 16 MB, sustained buffer-to-disk transfer rates are listed at 86 (RE2-GP), 98 (RE2), and 126 (RE3) MB/sec, and average latency is listed at 4.2 ms. The RE Series drives each carry a 1.2 million hours MTBF rating.

The key feature that differentiates the RE series drives from other WD offerings is their built-in Time Limited Error Recovery, or TLER. According to Western Digital, TLER allows the RE series drives to be more compatible with RAID controller implementations; producing less drive "fallout" as can be the result of a standard drive's extensive built-in error recovery procedures (I.E., because the drive may be unresponsive during such an error recovery operation, the RAID controller may mistakenly assume the drive has failed and remove access to it from the array). In essence, TLER limits the amount of time the drive can spend processing its own error recovery functions and thereby the drive responds quicker to the RAID controller (in effect, turning over the error recovery process to the RAID mechanism itself).

An additional RE series feature is the vendor's Rotary Acceleration Feed Forward (RAFF) technology, which, according to the vendor, optimizes the drives' performance when they are used in multi-drive systems such as storage arrays.

The RE Series drives are currently offered in three flavors: The previous generation RE2 drives, the next generation RE3 drives (with a dual processor design that increases the drive's performance 20% beyond that of the 2nd generation drives), and the RE2-GP, or "GreenPower" drives which feature power conservation features including Intelliseek (calculates the optimum speed of the actuator arm to reduce wasted movement), Intellipower (balances the actual spin speed of the platter to match needs and consumes less power on start up), and Intellipark (unloads recording heads during idle). Intelliseek is also featured in the RE3 drives.

The RE series drives are available now. Pricing for the new RE3s is listed from $79 (250 GB) to $119 (500 GB). The 1 TB RE2-GP is listed at $299.99.

Contact Western Digital for further information.