madd@bu-cs.BU.EDU (Jim Frost) (01/28/88)
In article <3505@batcomputer.tn.cornell.edu> dorin@tcgould.tn.cornell.edu (Stewart Johnson) writes: >I am told that a hardware reset button is a good idea if one has a hard >disk. Why? Spinning up and down the hard disk shouldn't really be done all the time. A reset switch allows you to reset the processor without powering down the whole system. This saves wear and tear on the drive. (There can also be head considerations but this isn't universal.) >I always park the heads before turning the machine off. What is the danger >of not doing so? A lot of fear over parking the heads has to do with real old drives. I had the (mis)fortune of being around once when someone powered down an external drive attached to an old Rainbow without performing normal shutdown procedures. The heads slammed into the disk and made this interesting noise that I'd appreciate never hearing again. New drives don't usually exhibit this type of behavior. A power down isn't really good for the drive, but doesn't usually hurt anything. If you fail to park the heads, they may be sitting over (on?) your actual disk surface. If the PC is moved around, it is possible to damage the surface of the disk and therefore the data. This is why nearly every disk manufacturer recommends parking the disk before moving your PC but very few recommend parking every time you turn off the computer. Usually it's only a problem if you're moving the thing. Many new disks have automatic parking; when the power fails, the heads retract to a "safe" place automatically. You don't need a program to do it for you. Most of the 20-40Mb disks DO NOT do this, but quite a few 70+Mb disks do. Almost all disks that have this feature have it documented somewhere (although I've seen disks that I know to be self-parking come without any indication of this ability). I almost never park the disk on PCs that I use because they're not going to be moved. But then again, I back them up all the time so it really doesn't matter to me that much. If you're worried about your data, you should probably park it. If you have any doubts about it, just remember that it doesn't hurt anything to park the drive, it just takes a little more time. jim frost madd@bu-it.bu.edu
dhesi@bsu-cs.UUCP (Rahul Dhesi) (01/28/88)
Re: Head parking.
Create a command called "bye" on every system you use. If it's a
mainframe, make "bye" an alias for "logout" or equivalent. If it's a
PC, make it a batch file or CED synonym that parks your hard disk.
Once typing "bye" is a habit whenver you're done with computing,
you won't think twice about it.
--
Rahul Dhesi UUCP: <backbones>!{iuvax,pur-ee,uunet}!bsu-cs!dhesibobr@zeus.TEK.COM (Robert Reed) (01/30/88)
I can think of one practical reason while running e-mess-dos. There have been occasions where I have so bolixed up my system that the normal control-shift-whatever to which the keyboard controller is supposed to listen will not reboot the machine. Without a reset button, I am forced to cycle power to boot the system, which cannot be good for the disk. -- Robert Reed, Tektronix CAE Systems Division, bobr@zeus.TEK
glz5913@ritcv.UUCP (01/30/88)
In article <3073@zeus.TEK.COM> bobr@zeus.UUCP (Robert Reed) writes: > >... Without a reset button, I am forced to >cycle power to boot the system, which cannot be good for the disk. >-- >Robert Reed, Tektronix CAE Systems Division, bobr@zeus.TEK Turn off the machine, wait 5-10 seconds (or until the drive stops) and then turn on the computer. Incidentally, a lot of clones have the plug (towards the back of the motherboard) for a momentary contact switch. If you have the technical manual for the motherboard, it should show where it is.
mvolo@ecsvax.UUCP (Michael R. Volow) (01/31/88)
For those not interested in hacking their machines, Irata - Reset (2562 E. Glade, Mesa, Az., 85204, 602 926 7969; $24.95 + $2 ship) was easy to install in my IBM-PC. I merely unplugged a cable from my power supply, plugged in the reset switch cable, and plugged in the original cable in piggy back, per their reasonably clear instructions. They offer several suggestions about where to locate the button, and provide a drilled slot blank if you have an extra. I didn't, and chose to drill a hole in the bracket of the hard disk controller (after temporarily disconnecting the bracket, naturally). It works fine, and I've been able to avoid the big red switch. However, I'm surprised that no manufacturer of OEM or after-market power supply has seen fit to include a small reset button (suitably guarded from accidental contact) integrated with it. Disclaimer: No connection with Irata; just happy to have their con- venient product. Michael Volow, M.D. Dept of Psychiatry, Durham VA Medical Center, Durham, N.C. 27705 919 286 0411 mvolo@ecsvax.UUCP
guest@vu-vlsi.UUCP (visitors) (02/01/88)
In article <139@ritcv.UUCP> glz5913@ritcv.UUCP (Gary L. Zeiger) writes: >In article <3073@zeus.TEK.COM> bobr@zeus.UUCP (Robert Reed) writes: >> >>... Without a reset button, I am forced to >>cycle power to boot the system, which cannot be good for the disk. >>-- >>Robert Reed, Tektronix CAE Systems Division, bobr@zeus.TEK > >Turn off the machine, wait 5-10 seconds (or until the drive stops) and >then turn on the computer. I hope everyone does this when they power down to reset their system, but does not reduce the worst part of the wear and tear on the disk (the starting up). >Incidentally, a lot of clones have the plug >(towards the back of the motherboard) for a momentary contact switch. >If you have the technical manual for the motherboard, it should show >where it is. Now, if IBM could only follow this bit of wisdom! ============================================================================== | Mark Schaffer | BITNET: 164485913@vuvaxcom | | Villanova University | UUCP: ...{ihnp4!psuvax1,burdvax,cbmvax,pyrnj,bpa} | | (Go Wildcats!) | !vu-vlsi!excalibur!164485913 | ============================================================================== please respond/reply to the above addresses and not to guest@vu-vlsi.UUCP
neese@cpedev.UUCP (02/02/88)
>I am told that a hardware reset button is a good idea if one has a hard >disk. Why? Beats me, other than it keeps you from powering down the system in the advent of a crash. This keeps the power supply from taking the completely unneccessary power hit from the drive on power-up. >I always park the heads before turning the machine off. What is the danger >of not doing so? Most drives will automatically park thier heads when power is removed. Although the cheaper drives do not. If you intend on moving the system, then you better park the heads. This is just a safe thing to do. More often than not you will be okay, but the penalty for not doing it is a complete loss of data. Not the best thing in the world to happen. >I have an IBM PC and a Seagate ST238 hard disk. >Thank you in advance for your help. Park this beast before moving or anything else. Roy Neese UUCP @ ihnp4!sys1!cpe!neese
keithe@tekgvs.TEK.COM (Keith Ericson) (02/03/88)
In article <139@ritcv.UUCP> glz5913@ritcv.UUCP (Gary L. Zeiger) writes: > >Turn off the machine, wait 5-10 seconds (or until the drive stops) and >then turn on the computer. Incidentally, a lot of clones have the plug >(towards the back of the motherboard) for a momentary contact switch. >If you have the technical manual for the motherboard, it should show >where it is. I've built lots of systems and installed the reset switch by putting a momentary-closure button wired between the "Power Good" wire and ground. The "Power Good" line is, in the AT and 386AT Clones I built, the first wire in the motherboard power connector, closest to the rear-panel of the machine. "Your mileage may vary. The check is in the mail. I'm from the government and I'm here to help you. Don't worry, it's only a cold sore. Of course I'll still respect you in the morning. Yes, I'm divorced. No, my wife never comes home from her meeting this early. Yes, OS/2 will solve all your problems. No, I won't co.." Well, you get the picture: I'm not responsible if you injure yourself, anyone or anything else with this information. keith
farren@gethen.UUCP (Michael J. Farren) (02/08/88)
>>I am told that a hardware reset button is a good idea if one has a hard >>disk. Why? Because it allows you to do a complete cold boot without powering down the disk drive. If the disk is powered down, and it doesn't have auto- parking (as most smaller disks do not), then the heads land wherever they happen to be. This will most likely not be a problem, but it could be - you could lose data. The reset button will allow the heads to keep flying, thus never touching the surface, thus preventing this type of data lossage. -- Michael J. Farren | "INVESTIGATE your point of view, don't just {ucbvax, uunet, hoptoad}! | dogmatize it! Reflect on it and re-evaluate unisoft!gethen!farren | it. You may want to change your mind someday." gethen!farren@lll-winken.llnl.gov ----- Tom Reingold, from alt.flame
madd@bu-cs.BU.EDU (Jim Frost) (02/11/88)
In article <662@gethen.UUCP> farren@gethen.UUCP (Michael J. Farren) writes: >>>I am told that a hardware reset button is a good idea if one has a hard >>>disk. Why? > >Because it allows you to do a complete cold boot without powering down >the disk drive. If the disk is powered down, and it doesn't have auto- >parking (as most smaller disks do not), then the heads land wherever >they happen to be. This will most likely not be a problem, but it could >be - you could lose data. The reset button will allow the heads to keep >flying, thus never touching the surface, thus preventing this type of >data lossage. This isn't necessarily true. In all but the cheapest (and the very very expensive) drives, the heads will not touch the surface of the disk unless the disk is moves (relatively) violently. This is why you usually need to park the heads only when you move the drive. Think of it this way: drives take several seconds to spin down. If the heads were only electronically suspended, they would lose suspension far before the drive stopped spinning. The heads would scrape across the surface of the disk, damaging both the heads and the disk, until the disk came to a full stop. Trust me, you'd hear it. I recall a time back in the CP/M days when a drive that just dropped the heads was turned off before doing a power down sequence. The noise that that thing made was enough to make anyone cry. The best reason for the reset switch is that the drive doesn't have to be spun up again. Spin up is the most strenuous time for a drive and also for the computer's power supply, and it is best to avoid doing it more than necessary. jim frost madd@bu-it.bu.edu
dbraun@cadev4.intel.com (Doug Braun ~) (02/12/88)
In article <19824@bu-cs.BU.EDU> madd@bu-it.bu.edu (Jim Frost) writes: > >This isn't necessarily true. In all but the cheapest (and the very >very expensive) drives, the heads will not touch the surface of the >disk unless the disk is moves (relatively) violently. This is why you >usually need to park the heads only when you move the drive. Think of >it this way: drives take several seconds to spin down. If the heads >were only electronically suspended, they would lose suspension far >before the drive stopped spinning. The heads would scrape across the >surface of the disk, damaging both the heads and the disk, until the >disk came to a full stop. Trust me, you'd hear it. > >I recall a time back in the CP/M days when a drive that just dropped >the heads was turned off before doing a power down sequence. The >noise that that thing made was enough to make anyone cry. This portion of his reply is incorrect. The heads are suspended by the air stream caused by the rotating disk. The heads are literally "flying" or "planing" above the disk. This has nothing to do with anything electronic. Winchesters usually have a tiny bit of lubricant on the disks to protect the heads when they do land as the drive stops spinning. More expensive drives will actually physically push the heads away from the disk at power-off, thus making the drive very shock-resistant when turned off. Other drives will move the heads to an unused area of the disk (the "landing zone") at power-off. The cheaper stepper-motor drives (which includes almost ALL <=20meg drives used with XT's, including the popular Seagate ST-238 and its brethren) just die when the power goes off, and the heads land where they may. On these you have to explicitly park the heads before power-off. The noise mentioned above is undoubtedly due to a mechanical brake that stops the rotating disks ASAP after power-off. Some drives have a brake with a little solenoid pulls the brake pad away from the motor rotor when power is applied. Other drives use a relay to short out the motor coils when power is removed, electrically braking the motor. Take apart a few of these beasties, and you'll know what's REALLY going on. Doug Braun Intel Corp CAD 408 496-5939 / decwrl \ | hplabs | -| oliveb |- !intelca!mipos3!cadev4!dbraun | amd | \ qantel /
bobmon@iuvax.UUCP (Bob, Mon) (02/12/88)
[Discussion: Why does a harddisk want a reset button?] In article <19824@bu-cs.BU.EDU> madd@bu-it.bu.edu (Jim Frost) writes: > >The best reason for the reset switch is that the drive doesn't >have to be spun up again. Spin up is the most strenuous time for a >drive and also for the computer's power supply, and it is best to >avoid doing it more than necessary. Turning the power supply off or on also induces momentary power surges in the chips themselves. These power surges in turn cause electrical and thermal stress in the chips; i.e., the chips "age". This might be worth doing a few times on new chips, to catch any that are going to suffer "infant mortality" anyway. Ordinarily, though, the circuits will last longer if they're constantly powered than if they're turned on and off a lot. (Naturally, they'll also last a long time if you NEVER power them up....:-) -- You TOO Can Defeat The 4-Line .signature Limit And Be Obnoxious To Your Friends And Neighbours!!!!! ...---... Charles Cabbage on the Difference Engine running SE grade 10W40 at UKnoWhere Babble@diffEQ bob,mon@iuvax.cs.indiana.edu Chucky on Ada The Slide Rules!"Spaceship Earth! There IS no substitute!"
farren@gethen.UUCP (Michael J. Farren) (02/12/88)
In article <19824@bu-cs.BU.EDU> madd@bu-it.bu.edu (Jim Frost) writes: >This isn't necessarily true. In all but the cheapest (and the very >very expensive) drives, the heads will not touch the surface of the >disk unless the disk is moves (relatively) violently. This is why you >usually need to park the heads only when you move the drive. This isn't true. One of the things that was added to drives with the advent of Winchester technology was heads which can be landed on the disk during a power-down. With the exception of only those drives which physically retract and lock the heads on power-down, ALL Winchester drives land the heads on the media itself when the disk stops spinning, and their design ensures that damage is minimal. You park the heads specifically to allow them to land on an area of the disk which does not have data written on it, rather than taking the small chance of damage. >If the heads were only electronically suspended, they would lose suspension >far before the drive stopped spinning. The heads would scrape across the >surface of the disk, damaging both the heads and the disk, until the >disk came to a full stop. Trust me, you'd hear it. Nope. The heads are aerodynamically suspended - they ride on a cushion of air that is formed as the disks spin. When the disks spin down, the cushion disappears, and the heads DO land on the disk. Their design, however, is such that the damage to the head, and the disk, is minimal. More expensive drives, like the Priam V70, actually retract the heads before they land, but this is NOT the norm for inexpensive disks. >I recall a time back in the CP/M days when a drive that just dropped >the heads was turned off before doing a power down sequence. The >noise that that thing made was enough to make anyone cry. Older disk drives were not designed to allow the heads to land - a head crash was literally that, and usually destroyed heads and disks. There is, or was, a pretty lucrative industry which specialized in supplying replacement head assemblys. -- Michael J. Farren | "INVESTIGATE your point of view, don't just {ucbvax, uunet, hoptoad}! | dogmatize it! Reflect on it and re-evaluate unisoft!gethen!farren | it. You may want to change your mind someday." gethen!farren@lll-winken.llnl.gov ----- Tom Reingold, from alt.flame
madd@bu-cs.BU.EDU (Jim Frost) (02/12/88)
In article <1691@mipos3.intel.com> dbraun@cadev4.UUCP (Doug Braun ~) writes: >In article <19824@bu-cs.BU.EDU> madd@bu-it.bu.edu (Jim Frost) writes: >>I recall a time back in the CP/M days when a drive that just dropped >>the heads was turned off before doing a power down sequence. The >>noise that that thing made was enough to make anyone cry. >The noise mentioned above is undoubtedly due to a mechanical brake >that stops the rotating disks ASAP after power-off. Some drives >have a brake with a little solenoid pulls the brake pad away >from the motor rotor when power is applied. Other drives use a relay >to short out the motor coils when power is removed, electrically >braking the motor. The noise I mentioned was of the heads destroying the surface of the disk. The drive was destroyed, a cost of several thousand dollars at the time, not to mention the loss of data. As for whether or not the drive heads actually touch the disk, I suppose you're right that they do on cheap drives, but the only drives I've worked on that appeared to do this were really old drives on an AT. They made an obvious "clunk" during spin down that always made me jitter. But recently I've been working with drives of 80 meg and up.... >Take apart a few of these beasties, and you'll know what's >REALLY going on. I liked it better when they encased drives in clear plastic so you could watch 'em run. Cheers, jim frost madd@bu-it.bu.edu
paula@bcsaic.UUCP (Paul Allen) (02/13/88)
In article <19824@bu-cs.BU.EDU> madd@bu-it.bu.edu (Jim Frost) writes: >In article <662@gethen.UUCP> farren@gethen.UUCP (Michael J. Farren) writes: >>>>I am told that a hardware reset button is a good idea if one has a hard >>>>disk. Why? >> >>Because it allows you to do a complete cold boot without powering down >>the disk drive. If the disk is powered down, and it doesn't have auto- >>parking (as most smaller disks do not), then the heads land wherever >>they happen to be. This will most likely not be a problem, but it could >>be - you could lose data. The reset button will allow the heads to keep >>flying, thus never touching the surface, thus preventing this type of >>data lossage. > >This isn't necessarily true. In all but the cheapest (and the very >very expensive) drives, the heads will not touch the surface of the >disk unless the disk is moves (relatively) violently. This is why you >usually need to park the heads only when you move the drive. Think of >it this way: drives take several seconds to spin down. If the heads >were only electronically suspended, they would lose suspension far >before the drive stopped spinning. The heads would scrape across the >surface of the disk, damaging both the heads and the disk, until the >disk came to a full stop. Trust me, you'd hear it. Excuse me? Electronically suspended? From other postings, I assume that Jim knows how disks work, but perhaps some clarification is in order here for those who really are curious why a reset button is desirable. The heads in Winchester drives are designed to rest on the disk surface when the power is off. When the disk is spinning, the heads are suspended aerodynamically in the wind that is dragged along by the platters. Due to the Bernoulli effect, the heads approach the disk surface very closely, but do not touch it. When the drive is in the process of spinning up or down, there is a period of time when there is not enough wind to keep the heads flying. During this time, the heads slide on the surface of the platters. Parking the heads moves them over an area of the disk that doesn't have data on it. Parking is advised before a move because a shock can cause the heads to *bounce* on the disk surface, resulting in loss of data. Some early drives (like my 5.5M Shugart) land a little roughly on power down, and need to be parked each time. But by the time the XT came out, the drive makers had figured out how to build drives that could be safely shut off without parking. Many of the drives that have come along since automatically park the heads on power-off. So, for just about any drive you're likely to see in a PC-class machine, you generally won't lose data if you turn the power off. >I recall a time back in the CP/M days when a drive that just dropped >the heads was turned off before doing a power down sequence. The >noise that that thing made was enough to make anyone cry. Sounds like a wonderful drive! It has a head crash if you don't power it down just right? What kind of drive was that? (I'm really curious. I toyed with the idea of hacking a hard disk into my old CP/M system, but never had the cash.) >The best reason for the reset switch is that the drive doesn't >have to be spun up again. Spin up is the most strenuous time for a >drive and also for the computer's power supply, and it is best to >avoid doing it more than necessary. THIS is why a reset button is a nice thing to have! >jim frost >madd@bu-it.bu.edu Paul -- ------------------------------------------------------------------------ Paul L. Allen | paula@boeing.com Boeing Advanced Technology Center | ...!uw-beaver!ssc-vax!bcsaic!paula