djlinse@phoenix.Princeton.EDU (Dennis John Linse) (12/12/88)
I promised a summary of responses back in June. It is probably about time to do the summary. I probably won't get anymore responses. First my original question and then the responses. You will notice that they are decidedly mixed. No decision has been made around here except to leave things as they are. Quite the radical choice :-) In article <3170@phoenix.Princeton.EDU> I wrote: >A quick gathering of opinions. > >How often should we turn off and on our computers and peripherals? >Is it better to leave them on all the time? All day? Only when in use? >Some combination of the above? > >We specifically have IBM PC's which we leave on all of the time, a Mac >II which stays on most of the time, a unix box which stays on all of the >time, a Laserwriter that stays on all of the time, and an Imagen laser >printer that is only turned on when needed (it has a fan with an >obnoxious high pitched sound). > >Would it be better to turn them all on in the morning and off at night? >What is the break-even point? > ------------------- From: msmith@topaz.rutgers.edu (Mark Robert Smith) I'd say if you use them every day, leave them on all night. I would power them down for impending thunderstorms, as they get bad down your way. If you leave them on, be sure to turn off the monitor AND get a screen blanker (automatic). Mark -------------------- From: steinmetz!davidsen@uunet.UU.NET (William E. Davidsen Jr) One of our repair people did a survey of how broken equipment was used, and how long it had run before failure. He noted that daily power cycling reduces equipment life, turning off on the weekend is a break even. The only component which really has a lifetime in power on hours is a hard disk. I leave mine on all the time, to run things in the background. -- bill davidsen (wedu@ge-crd.arpa) {uunet | philabs | seismo}!steinmetz!crdos1!davidsen ----------------------- From: Michael Stevens <mstevens@tekig4.len.tek.com> As a test engineer for a large company, and having worked on products from power supplies to workstations and displays (terminals), the greatest stress on a product is at poweron. This is especially true for products with switching supplies (which almost all major new products - like IBMs - have) and display devices (CRT's / Monitors / Terminals). Also, every time you power down a small magnetic flux occurs at the heads of the hard and floppy disk devices, so if the heads are above data portions of the memory at power on/off, the data can become weaker with time. Eventually it could be lost or become intermittent. This gives a case for leaving the system on. The greatest enemy of a computer system active memory device (floppy, hard disk) is dirt. By this I mean anything bigger than a small smoke particle. Another consideration is MTBF - mean time between failures. This is a number typically derived statistically given a base set of assumptions on how often a system will be turned on/off and the effect that has on the componets, as well as general use (like with drives). This gives a case for turning the system off. My recommendation: If you have a clean environment 24 hrs a day and fire protection (yup, the little buggers can catch fire all by themselves) leave your system up, but park the heads on the hard disks when they aren't in use. By the way, this may lead to a security issue (unauthorized use). If you have janitors or a busy little clean freak (wife/husband) wandering around vacuuming whenever your system is running or if it is a very dusty day and you aren't in a controlled environment, shut it down. Your pocketbook will thank you. Typically, home users are best off turning them off since the on time is very small compared to the off time. Also home is a dirty place. Office workers with their own machines are near the break even point (generally clean environments, systems in used ~10 hours per day). If your system is used more than 12 hrs and its in a clean environment, I'd leave it on (but again, park the heads). For what it's worth, and the opinions are solely my own, not as professional advice thru my current employer. Mike Stevens -------------------------- From: Mr Jack Campin <jack%cs.glasgow.ac.uk@NSS.Cs.Ucl.AC.UK> We keep our Mac hard disks on all the time, but turn the Macs off in the evening. Seems to work; the disk is more likely to be damaged by switching on, the Mac by continuous heat. -------------------------- An IBM PC will fail after toggling the power switch 1000 times plus or minus 100%. This statistic circulated as an internal IBM memo during alpha test. A mac-II will fail if you look at it wrong ;-). The hardware design is young and fragile. I suspect powering it down is better because it cooks when running. If the machines are used more than 12 hours per day, don't cycle power; otherwise, expect failures after 5 years of daily use (1000 power-off/ons). -Mitch -- -Mitchell F. Wyle wyle@ethz.uucp Institut fuer Informatik wyle%ifi.ethz.ch@relay.cs.net ----------------------------- From: umix!ames!elroy.jpl.nasa.gov!jplgodo!mustang!lex (Lex Mierop) shut off the PC's leave the unix box on if the Laserwriter is used by the unix box at night, leave it on I have no idea about the Mac II. I too hate noisy fans. The reasoning is as follows: no work gets done on the PCs at night. If you get a power glitch at night you risk killing your PCs. unix boxes do stuff at night. leave 'em alone. ----------------------------- From: rainier!carola!bertil@uunet.UU.NET (Bertil Reinhammar) OK: At my workingplace we have some 15 SUN ( various ) another 40 (!) comming in during the autumn, a GOULD PN6000 unixbox, a VAX 750, a microVAX and IBM/AT. As far as I know, ALL machines are running 24h around. Possibly the users of IBM/AT turn theirs off due to bad noise problem. That also applies to SUN3/50 before fix of the fan. Why ? Well there is no reason to turn the stuff off unless it disturbs you. Even all the terminals are are left on unless they show a bad history. Most equipment simply gets more worn by turning off/on than being left on, once installed. Possibly one can argue that it consumes a lot off power. Probably cheaper than wearing on equipment and besides, it saves the heating bill for the house ( at least here in Sweden :-) which applies for all workstations. Machines in computer rooms with special cooling systems are very SELDOM turned off anyway. One last argument for turning off: It saves the screeen for the workstation. However, thet is a NULL reason since it is better to turn intensity down or have some kind of blank program running ( you know the kind having a small icon or something jumping around randomly so as to prevent burning marks .) -------- -- Found at the top of a looonnng homework assignment: "Activity is the only road to knowledge" G.B. Shaw