Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!ukma!psuvm.bitnet!cunyvm!ndsuvm1.bitnet!nu013809 From: NU013809@NDSUVM1.BITNET (Greg Wettstein) Newsgroups: comp.sys.ibm.pc,comp.misc Subject: Re: Leaving AT on overnight (good/bad) Message-ID: <261NU013809@NDSUVM1> Date: Fri, 14-Aug-87 08:34:34 EDT Article-I.D.: NDSUVM1.261NU013809 Posted: Fri Aug 14 08:34:34 1987 Date-Received: Wed, 19-Aug-87 02:38:02 EDT References: <1246@bloom-beacon.MIT.EDU> <768@custom.UUCP> 202@ttrdd.UUCP Organization: North Dakota Higher Education Computer Network, Fargo, ND Lines: 74 Xref: mnetor comp.sys.ibm.pc:6829 comp.misc:1044 DISCLAIMER: Author bears full responsibility for contents of this article. As the computer coordinator for the College of Pharmacy I have been dealing with the on vs off controversy for about 8 years now. It has been my experience that computer equipment and peripherals which are left on continuously have far fewer problems than those which are cycled with any degree of consistency, even once a day. The first personal computer I dealt with after having a series of Data General mini-computers was a Zenith Z-158 with one of the first 10 megabyte hard disks which ZDS started putting in their computers. It was left on 24 hours a day for 2 to 2 1/2 years before the (what would be considered the fairly primitive) hard disk gave out. I have another Zenith Z-158 with a Seagate ST-225 hard disk in one of our hospitals which has been running continuously now for 2 years with nary a glitch. On the other hand our research group on campus has an IBM PC which is now on its third hard disk in about three years. The first disk lasted only about 1 year as it was cycled on and off every time somebody wanted to use it. I managed to convince them that they should at least let it run all day and turn it off at night it they wanted to. This was done with the second hard drive and this one lasted slightly longer than a year. I put a Seagate ST-225 in when the second drive burned out and strongly advised leaving it run 24 hours a day. The drive has been running flawlessly for over a year now with no difficulty. A good friend of mine who teaches in the Electrical Engineering department here at NDSU was the individual who started me on my crusade to keep equipment running all the time. He had told me that as far as he knows there have been no definitive studies that indicate that semi-conductor devices (integrated circuits) "wear out". In the vacuum tube era (which I experienced first hand) this was not the case. These devices depended on emission from thorium-oxide coated filaments. The filaments had a finite lifespan which could be preserved by powering the device down when not in use for extended periods of time. What appears to be the case with semi-conductor devices is that while they do not "wear out" they can be damaged by voltage spikes and power surges induced by the power cycling process. One of the individuals posting a message in this chain indicated that he had never heard of a terminal wearing out. I wish that our organization had his luck. Our first attempt at word processing was with a multi-user product called T.I.P.S. marked by IPTC of Palo Alto California. This word-processor supported our five secretaries and was run under RDOS on a Data General Nova/4X. Each secretary had an ADM-5a as a terminal. I advised them to leave the terminal on all the time and to simply turn down the display whenever they wanted to leave the terminal for longer than 5 minutes. I couldn't convince them that this was a good idea and the terminals got turned off every night and sometimes a couple of times a day. To make a long story short none of those terminals lasted much over a year, all died of various electronics problems. At the time we purchased the terminals we actually bought six terminals and the sixth went on the Nova as the operator console. That terminal ran continuously for three years 24 hours a day until we sold the Nova and went to PC's. I moved the terminal down to my lab office and its still running 24 hours a day, 2 years after we took it off the Nova. These results are not scientific or statistically rigorous but they do serve as examples. My experience has taught me to worry more about environmental considerations such as excessive heat and the biggest problem (especially here in the prairie) large amounts of dust and dirt getting into the equipment. As always, G.W. Wettstein NU013809@NDSUVM1 When not at the above E-MAIL address I can be found in Davenport, North Dakota, roping the hind feet of Hereford cattle . . . very rapidly.......