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Typical Failures And Data Losses

Study: A Look At Hard Drive Reliability In Russia
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Seagate Bitten by the "CC Fly"

Seagate's results stem mainly from the 500 GB to 1.5 TB Barracuda 7200.11-series. These products comprise over 65% of all failed Seagate drives received by Storelab. Most drives failed within the first one and a half years, and thus were still covered by the warranty. In comparison, the older Seagate 7200.10-series is much sturdier and only accounted for 35% of failed Seagate drives. The most common failure cause for the 7200.11 was faulty firmware, which would issue the error code "000000CC." This led the Storelab engineers to coin the term "CC fly" (tsetse fly). Faulty drives would slow down and subsequently die after rebooting.

There were other errors as well, and not just from Seagate. The most common was wedging of the drive's axle. This happens occasionally to all hard drive brands. High-capacity hard drives use three or more magnetic disks, or platters. The additional platters increase the load on the axle, and the resultant physical stress leads to motor failures. A drop of only 20 cm can be enough to wedge the axle, which will first manifest through increasing hard drive noise and vibration. Seagate uses a new technology in the 7200.12 and later drives to counter this issue. We will have to wait for more long-term studies in order to find out if matters have been truly remedied.

Western Digital in the Background

As for Western Digital's failures, 59% of the company's examined hard drives had a capacity of up to 500 GB, and their average lifespan was 3.5 years. The remaining 41% exceeded 500 GB. Due to their construction and additional platters, these larger models are less durable, exhibiting an average lifespan of only 1.5 years. Storelab notes that read/write head failure is somewhat characteristic for WD drives. Failures primarily occur as a result of physical impact or overheating (WD heads can be sensitive at temperatures above 45°C).

Western Digital's construction makes drives particularly vulnerable to shocks and pressure. Unlike other manufacturers, WD does not secure the hard drive axle with a separate screw to the drive cover. Because of this, pressure exerted on the housing or cover can shift the axle, resulting in it changing its angle, and then damaging the platters. The axle's attachment to the cover is another reason. If the cover is moved, the engine may be blocked. Except for this vulnerability, though, WD hard drives are mechanically and electronically reliable.

Wedged Axles from Toshiba/Fujitsu and Samsung

Only 2.5" notebook hard drives from Toshiba/Fujitsu were evaluated in this study, and the average lifespan of these drives was two years. Their most common problem was wedged axles due to defective fluid bearings, usually from aging. The axles on the Toshiba/Fujitsu drives are attached to the cover, but the cover is very thin and subject to deformations. Over time, lubrication liquid in the bearings can evaporate. This gradually increases the friction in the socket, producing splinters that eventually eat away at the axle. Wedging of the axle is one of the worst things that can happen to a hard drive, and data recovery may not always be possible.

Another common reason for failures in these notebook hard drives is the damage caused by the read/write heads falling on the moving platters. Normally these heads float on a thin layer of air over the spinning platters, but if something happens and the two come in direct contact, the platters are usually so badly scratched that the hard drive is unusable. You might hear a faint hum, the drive will be detected in the BIOS, but it may not work anymore. Data is almost always lost if this happens. Mechanical damage from these head crashes is the most common cause of failure in Samsung hard drives.

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