Using a USB thumb drive for backups?
in [Mac Systems]
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From: Tom Stiller on 23 Dec 2009 07:13 In article <michelle-371A8A.21295822122009(a)news.eternal-september.org>, Michelle Steiner <michelle(a)michelle.org> wrote: > In article <tom_stiller-86831D.23014322122009(a)news.individual.net>, > Tom Stiller <tom_stiller(a)yahoo.com> wrote: > > > With enough current, _any_ voltage can kill you. > > > > Don't forget, E=I*R. For a given resistance, you don't get either > > voltage or current without the other. > > The human body, being mostly water with dissolved electrolytes, has a > fairly low R. That doesn't change the fact that one can't get enough current with _any_ voltage. -- Tom Stiller PGP fingerprint = 5108 DDB2 9761 EDE5 E7E3 7BDA 71ED 6496 99C0 C7CF
From: Nick Naym on 23 Dec 2009 12:23 In article michelle-7431A9.22333022122009(a)news.eternal-september.org, Michelle Steiner at michelle(a)michelle.org wrote on 12/23/09 12:33 AM: > In article <017a1ca4$0$3201$c3e8da3(a)news.astraweb.com>, > JF Mezei <jfmezei.spamnot(a)vaxination.ca> wrote: > >>> The human body, being mostly water with dissolved electrolytes, has a >>> fairly low R. >> >> Remember that we are ugly bags of mostly water :-) > > You may be ugly. Bessie Braddock: "Winston,...you are disgustingly drunk." Winston Churchill: "Bessie,...you are disgustingly ugly. But tomorrow I shall be sober..." -- iMac (24", 2.8 GHz Intel Core 2 Duo, 2GB RAM, 320 GB HDD) � OS X (10.5.8)
From: J.J. O'Shea on 23 Dec 2009 08:27 On Tue, 22 Dec 2009 08:15:42 -0500, Paul Sture wrote (in article <paul.nospam-0F5DED.14154222122009(a)pbook.sture.ch>): > In article <1jb0xkw.1pg4j9z1c4ajswN%nospam(a)see.signature>, > nospam(a)see.signature (Richard Maine) wrote: > >> JF Mezei <jfmezei.spamnot(a)vaxination.ca> wrote: >> >>> nospam wrote: >>> >>>> i didn't say there weren't. however, some new drive mechanisms use less >>>> power than older ones. >>> >>> A 600 meg disk in the mid 1980s required a 10amp 115VAC circuit for each >>> drive, and used a 1/3HP motor to turn the disk. > > The 250MB disk drives I was using in the early 1980s had a mechanism to > fire each one up in sequence so that during startup the main circuit > breaker didn't flip. > >> And weighed about 175 pounds and cost about $30,000 - at least one model >> I recall did. I think those were the right numbers. I distinctly recall >> helping our hardware guy remove one from its rack. I wasn't very smart >> about how I positioned my hold on it. Once we were holding the full >> weight, it seemed like the thin metal rail that I was holding it by was >> cutting through my fingers. I had this horrified vision of dropping and >> breaking a $30k piece of government equipment. I managed to avoid that, >> but I still recall the pain. > > I don't recall how much those 250MB disk drives weighed but they were > washing machine sized rather than rackable. Two gorilla sized guys were > needed to get them upstairs. They did this stuff for a living and still > turned the air blue with their curses. > > If you're talking about the old CDC disk packs and disk drives like these <http://www.bitsavers.org/pdf/cdc/discs/brochures/ProductLine_May73.pdf> I can say that the 300 MB disk packs weighed 25 pounds each (and cost US$10,000 when new...) and the drives for them weighed in excess of 500 pounds and were, yes, the size of a washing machine. A big washing machine. The first place I worked for had three CDC 9790 units. We did not move them unless we had to, and when we did, we got out the trolley and a couple guys from Motor Maintenance. The damn things did move all by themselves when in operation unless their feet were properly set. This tended to cause head crashes, resulting in our needing to replace the disk pack ($10k, remember) and all 20 of the read-write heads at $512 each, plus recalibrating the drive with a $25k engineering disk pack... and if any of the replacement heads weren't properly set, the engineering pack might crash, requiring the replacement of a all 20 heads _and_ getting a new engineering pack. That got old real fast and we replaced them with 250 MB fixed disks which lived in one of the racks. And, of course, we had to get out the trolley and the boys from Motor Maint to move the silly things back to where they were supposed to be... At about the same time I had sitting on my desk at home a Mac 128 updated to Plusdom to which was attached a 40 MB drive. My Mac had 4 whole MB of RAM (the $1.5 million supermini had 5.5 MB...) and a 32 bit CPU running at 8 MHz (the supermini was 24 bit, yes, really, 24 bit, running at 5 MHz...) so my home machine had a fairly significant fraction of the total storage available to the supermini and was faster and had better graphics as well. (The supermini had VT-100 class green screens, except for the control room, where there were 19" colour screens for the system control staff...) Of course, the smallest capacity thumb drive I still have has more capacity than the disk pack, (512 MB...) and I can get a brand new 4 GB thumb drive for under $15, probably for under $10 if I try. -- email to oshea dot j dot j at gmail dot com.
From: Nick Naym on 23 Dec 2009 12:25 In article tom_stiller-2DECC3.07134423122009(a)news.individual.net, Tom Stiller at tom_stiller(a)yahoo.com wrote on 12/23/09 7:13 AM: > In article <michelle-371A8A.21295822122009(a)news.eternal-september.org>, > Michelle Steiner <michelle(a)michelle.org> wrote: > >> In article <tom_stiller-86831D.23014322122009(a)news.individual.net>, >> Tom Stiller <tom_stiller(a)yahoo.com> wrote: >> >>> With enough current, _any_ voltage can kill you. >>> >>> Don't forget, E=I*R. For a given resistance, you don't get either >>> voltage or current without the other. >> >> The human body, being mostly water with dissolved electrolytes, has a >> fairly low R. > > That doesn't change the fact that one can't get enough current with > _any_ voltage. ??? -- iMac (24", 2.8 GHz Intel Core 2 Duo, 2GB RAM, 320 GB HDD) � OS X (10.5.8)
From: isw on 24 Dec 2009 01:56
In article <C757BCBE.4E351%nicknaym@[remove_this].gmail.com>, Nick Naym <nicknaym@[remove_this].gmail.com> wrote: > In article tom_stiller-2DECC3.07134423122009(a)news.individual.net, Tom > Stiller at tom_stiller(a)yahoo.com wrote on 12/23/09 7:13 AM: > > > In article <michelle-371A8A.21295822122009(a)news.eternal-september.org>, > > Michelle Steiner <michelle(a)michelle.org> wrote: > > > >> In article <tom_stiller-86831D.23014322122009(a)news.individual.net>, > >> Tom Stiller <tom_stiller(a)yahoo.com> wrote: > >> > >>> With enough current, _any_ voltage can kill you. > >>> > >>> Don't forget, E=I*R. For a given resistance, you don't get either > >>> voltage or current without the other. > >> > >> The human body, being mostly water with dissolved electrolytes, has a > >> fairly low R. > > > > That doesn't change the fact that one can't get enough current with > > _any_ voltage. It's lucky you are still alive. For extra credit, explain why power line technicians wear all that protective gear, when they work on live high-tension lines. Isaac |