Path: utzoo!attcan!uunet!wa3wbu!john From: john@wa3wbu.UUCP (John Gayman) Newsgroups: comp.sys.ibm.pc Subject: Re: Leaving the hard disk on continuously Summary: this is rare Keywords: hard disk park - DON'T DO IT DAILY!!!! POWER OFF AT NIGHT!!!! Message-ID: <609@wa3wbu.UUCP> Date: 21 Jul 88 01:54:54 GMT References: <12184@agate.BERKELEY.EDU> <7837@watdragon.waterloo.edu> Distribution: na Organization: WA3WBU, Marysville,PA Lines: 53 In article <7837@watdragon.waterloo.edu>, ajmyrvold@violet.waterloo.edu (Alan Myrvold) writes: > I heard from an almost reliable source that parking the heads on a hard > disk actually retracts the thingamabob that reads the disk. Acording to > my source, the joint which retracts the thingamabob becomes sloppy > after overuse, causing it to skip on the media surface, bringing up > chips of the magnetic media which scrape the **** out of the drive as > the head goes round. > I beleive what your source might be referring to is that some very large drives, especially high capacity 8" drives actually "cam" the heads up off the platter in the "parked" position. You won't find very many of the 5 1/4 hard drives that most people use with this type of actuator. I could be made to beleive that repeatedly "loading" and "unloading" the heads could eventually crash or pit the platter although this in itself would be rare. Most of the drives in use in PC's and Mini's are built in such a way that the heads *never* actually leave the platter ---- ever. Whatever the positioning mechanism, be it servo motor or voice coil, the heads never leave the platter. On these drives when they are in the "parked" position, it simply means that the heads have been placed over a cylinder that has been designated as the "landing zone". The idea here is that if the disk takes a shock (like in shipping) and scratches or otherwise harms the disk platter, the effected area will be the "landing zone" and not some area of the disk where good data resides. If you don't park the drive, then the heads will basically stay positioned over the cylinder they were last at (at least with servo positioners). The exception here is with a lot of the "voice coil" positioning systems. Most of these are auto-parking. When you turn the drive off, you will hear a mild "clunk", this is the head mechanism being tossed out and "latched" at the landing zone cylinder, which is usually all the way towards the inside closest to the spindle. Once powered up, the selenoid energizes and allows the head assy to return to its position at track zero, re-calibrate or do whatever else it wants to. With this in mind, I can see no reason why "parking" a disk would be harmful. It simply means the heads stay positoned in the landing zone and not some random data cylinder. By design, you normally do not format out to, or use the landing zone cylinder. I hope this has cleared up some of the questions anyway. This sure is a hot topic on the net every couple months. :-) This and twisted disk cables. :-) :-) John -- John Gayman, WA3WBU | UUCP: uunet!wa3wbu!john 1869 Valley Rd. | ARPA: wa3wbu!john@uunet.UU.NET Marysville, PA 17053 | Packet: WA3WBU @ AK3P