rc2o+@andrew.cmu.edu (Richard Lee Chung) (08/02/90)
A while ago I was asking for some help with my LaCie 40 Meg HD. The inside mechanism is made by Connor. The funny thing is that I was really frustrated when it was not booting so what did I do? I banged it against the desk. Of course it starts working again but every once in a while it would have the same troubles. I am wondering if it is the humidity and such. I know that I should just get another HD but I really would like to avoid that if I can. Anyone know what's going on? no hh Rich
briand@tekig5.PEN.TEK.COM (Brian D Diehm) (08/03/90)
> A while ago I was asking for some help with my LaCie 40 Meg HD. >The inside mechanism is made by Connor. The funny thing is that I was >really frustrated when it was not booting so what did I do? I banged it >against the desk. Of course it starts working again but every once in a >while it would have the same troubles. I am wondering if it is the >humidity and such. I know that I should just get another HD but I >really would like to avoid that if I can. Anyone know what's going on? This is a common problem with modern, polished-surface high density hard disks. The heads are spring loaded to press down on the medium (but only very slightly). When the disk spins, it carries a layer of air with it, and this air rushing by keeps the head above the platter, again, only a very very short distance. This btw is what "Winchester" means. Well, when the platter isn't spinning, the heads touch the medium. With older style lower density media, the surface was rough enough that there was no problem - the surface looked a lot like the surface of a videotape. Newer media are actually polished to the point that they look like a mirror. The polished head touching the polished medium during off time can generate a problem of "sticktion" (you bet, ma'am, that's a real technical term). This makes the two stick together by simple adhesion. The drive motors on disks are high speed but EXTREMELY low torque, they simply don't have the power to break the sticktion and start the drive. The head drive mechanism is usually even weaker. The result? A disk that won't start. I have seen a disk at the company in-house repair facility where sticktion was SO strong that it tore one of the heads off the arm. You can turn this drive 1/4 turn (and break the sticktion), only to have it stick again in seconds. No, this disk has never had any gummy solution in it, it is still mirror-polished. It is now a conversation piece; generally it generates this very conversation. You can usually break the sticktion by a sharp rap, which gives you some time to start the disk before sticktion redevelops. ONCE A DRIVE SUFFERS STICKTION, IT WILL FAIL CATASTOPHICALLY SOON BECAUSE OF STICKTION (as a general rule; there are no absolutes). The way to avoid future sticktion is to NEVER POWER OFF A "STICKTIONED" DRIVE THAT YOU HAVE SUCCESSFULLY RESTARTED. Of course, you really want to replace the drive as soon as possible. There is a school of thought in our repair facility that says EVERY drive ever made will eventually die of sticktion, if it doesn't die of something else sooner. Others deny the inevitability of this fate. -- -Brian Diehm Tektronix, Inc. (503) 627-3437 briand@tekig5.PEN.TEK.COM P.O. Box 500, M/S 47-780 Beaverton, OR 97077 (SDA - Standard Disclaimers Apply)