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Seagate U5 ST340823A
  November 14, 2000 Author: Eugene Ra  
Evaluation unit provided by Seagate Technology.


Seagate's U5 represents the fifth-generation of Seagate's low-cost, entry-level hard disk solution. Don't be fooled by its name: the U5 is the successor to the U10. Judging from a field that grows ever more crowded, demand for value-class drives continues to come along strongly. Though such disks aren't of much interest to enthusiasts and power users seeking storage solutions for their own systems, they're found almost everywhere. It's important to know which units stand out when weighing purchase decisions for low-cost systems. The hard disk remains as the single most expensive unit in such systems... let's make sure those dollars are spent wisely.

The U5's specs are promising. Due to low measured demand, Seagate chose to sit out of the 15 GB/platter cycle, jumping directly to 20 gigs per disk. The U5 flagship features two platters, yielding a capacity of 40 gigs. Like most of its competitors, excepting only Quantum, Seagate has stuck with tried-and-true 5400 RPM spindle speed for its budget line. Specified seek time is quite impressive. Though all its competitors claim average seeks of at least 9.5 milliseconds, Seagate specs the U5 at a speedy 8.9 ms. Buffer size remains a relatively light 512k. Seagate considered 1024k of cache, but decided that the performance improvement wasn't worth the extra cost. Though it's a value-class drive, the U5 is backed by a full three-year warranty.

The U5 is one of the first of a new breed of drives that ships exclusively with the ATA-100 interface. Remember that since ATA drives have yet to break sequential transfer rates greater than even 40 MB/sec that ATA-66 (and in most cases, even ATA-33) interfaces will run the drive with optimal performance. Our testbed remains equipped with a Promise Ultra66 controller.

WB99/Win2k Low-Level Measurements

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Click here to examine the STR graph for this drive

We're disappointed to report that the U5 falls far short of meeting its promising 8.9 millisecond seek time. Our measurements place the drive's access time at 19.4 milliseconds. This figure is easily the highest access time we've ever recorded... worse than even the 4400 RPM, 12 millisecond seek Quantum Fireball lct15. Subtracting the standard 5.6 milliseconds associated with 5400 RPM rotational latency yields a measured seek time of 13.8 milliseconds... nearly 5 ms off the mark.

Sequential transfer rates, on the other hand, are respectable. The Seagate's outer-zone measurement of 31.6 MB/sec edges out scores from competing Fujitsu and IBM disks. Likewise, its inner-zone score of 20.7 MB/sec sets a record for a 5400 RPM drive.

So, how do these rather unique scores translate into high-level performance? Let's move on and discover.

WB99/Win2k WinMarks

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Though firmware optimizations aid it in trouncing the Quantum Fireball lct15, the U5 can't keep up with the rest of the competition. For example, it lags behind the category-leading Maxtor DiamondMax VL40 by 20% in the Business Disk WinMark 99. The margin grows worse in the High-End WinMark where Seagate's unit trails by more than 25%.

IOMeter Performance

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The U5's poor access time leads it to a pounding in the seek-intensive IOMeter Workstation Index (a normalized average of our Light, Medium, and Heavy loads). Its score of 100.9 falls over 27% behind the IBM Deskstar 40GV. Even a comparison against the Quantum Fireball lct15, hardly a star in our IOMeter suite, shows the Quantum besting the Seagate by 12%.


The U5 is a two-platter drive that's optimized for minimal power consumption and noise output. In this regard, it succeeds. The drive operates quietly and cool to the touch. It can be integrated into all systems without a problem.

Seagate takes pride in pointing out that the U-series drives are the most successful in history based on unit sales. Most readers, involved in IT or other computer-related professions, are bound to run into such drives. Even so, it's hard to recommend the U5 for those looking to build a low-cost machine or those looking for an inexpensive upgrade. The performance is simply not there. To its credit, the U5 is among the quieter drives we've used. It also features a robust three-year warranty. But there are other drives that offer similarly quiet operation combined with substantially better performance. In the end, it's those competing drives that offer the more attractive package.

Seagate U5 ST340823A
Estimated Price: $179
Also Available: ST330621A (30.6 GB); ST320413A (20.4 GB); ST315311A (15.3 GB); ST310211A (10.2 GB)
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