Click of death
From Wikipedia, the free encyclopedia
Click of death is a term that became common in the late 1990s referring to the clicking sound in disk storage systems that signals the device has failed, often catastrophically. The term is also used specifically to refer to the failure of portable Iomega Zip drives or cartridges. The "click of death" can also be an informal warning system before the data on a data drive is lost.
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[edit] Iomega Zip
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Iomega Zip drives were prone to developing misaligned heads. Dust inside the Zip disks or dirty heads caused by oxide build-up could misalign the heads, but in newer devices it was due to poor quality control and manufacturing defects in the drive itself. Magnetic fields could also cause the drive heads to become misaligned, as the drives were not internally shielded from external magnetic fields. The heads would cause the data on the cartridge to become misaligned, rendering it unreadable. The Zip cartridges would also wear out, grow defects, or otherwise lose all four 'Z tracks'. If all four redundant 'Z tracks' were lost, the cartridge would be unusable since retail drives are unable to low-level format the disks.
With a malfunctioning drive or cartridge, the drive heads would try to read the Zip disk, but not find a good Z track or hit a bad spot during a read operation. As part of the drive's retry program, the controller would quickly snap the head arm back into the drive and out again, producing specific number of 'clicks'. This happens each time a data request fails - the drive parks the heads to calibrate them and presumably clean them. Parking and relaunching would continue until the data was recovered or a set number of attempts was reached.
The Zip drive had a very low-cost and revolutionary linear actuator to move the read/write head back and forth on the Zip disk media. This actuator slid back and forth on a single thin steel rod using two jewel bearings much like those found in watches. Under normal drive use, the actuator was under the servo control of the drive. If the drive had its power removed inadvertently by being unplugged or power outage, the read/write heads would be pulled off the disk by a power-loss circuit. This was to prevent damage by the heads being left on the media. When the actuator was removed in this manner, it would slam to a stop at the end of its travel. This violent stopping of the actuator could damage the fragile suspension system of the read/write head. To protect from this damage, the drive designers placed a small donut shaped foam washer at the end of the thin steel bearing rod the actuator slid on.[citation needed] A cost reduction effort within Iomega manufacturing decided that to reduce the cost of the drive they should remove this 2 cent part. The Zip drives that followed for a several month period are those which exhibited the click of death. Once this omission was discovered by the drives original designers and put back into the design the Zip drive's click of death disappeared.[citation needed]
In rare cases, a Zip cartridge with disk edge damage could rip off the heads in a Zip drive. The damaged disks could go on to damage the heads of any other drive in which they were used. A previously good drive would click as if a miswritten cartridge was inserted. Replacement drives had a warning about damaged ZIP cartridges on a peel off label and quick visual inspection instructions.
A lifetime warranty on the 100 MB cartridge was misleading to the actual cartridge life and future products like the 250MB offerings carry a 5 year or less warranty from Iomega.
Iomega received thousands of complaints about the click of death, but denied all responsibility — often claiming, to the fury of Zip drive owners, that the problems were caused by the use of (functionally identical) third-party media. A class action suit was filed against them in September 1998. (Rinaldi v. Iomega Corp., 41 U.C.C. Rep. Serv. 2d 1143) The case was settled in March 2001 and Zip drive owners were given a rebate toward the future purchase of an Iomega product.
[edit] Hard disk
On a hard disk system, the click of death refers to a similar phenomenon, generally a read/write error during a seek. The hard disk has a hard error (hardware failure that cannot be undone by rebooting) or servomechanism failure, the head actuator will buzz and click as the drive tries to recalibrate. In most cases, the defect is due to physical abuse or a manufacturing error. The cause of the read/write errors is often due to the failure of the read/write heads' preamplifier, a small chip usually found soldered to the flexible cable on the actuator of modern hard drives. IBM's storage division had their own click of death problems in 2001 with the mass failure of their popular Deskstar, dubbed "Deathstar", 75GXP hard disks.
[edit] Apple iPod
In more recent years, this term has also been used to describe hard disk failure in Apple's iPod.[citation needed] iPod hard drives that click usually mean they are having problems finding information. The clicking sound comes from the arm going back and forth over the hard disk drive. These hard drives are sometimes repairable.
