Jihad needs scientists
in [Design]
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From: Ken Smith on 7 Mar 2007 09:46 In article <esm9f6$8ss_002(a)s1012.apx1.sbo.ma.dialup.rcn.com>, <jmfbahciv(a)aol.com> wrote: >In article <esju3h$1a4$2(a)blue.rahul.net>, > kensmith(a)green.rahul.net (Ken Smith) wrote: [.....] >>Having multiple disks connected to a single disk drive controller >>electronics gives absolutely no advantage and a few disadvantages. > >I know that one can have multiple structures on one drive. Has >the need of having one structure on multiple drives gone away? No, it hasn't gone away completely. There is a lot less need for logical volumes to span multiple disks today. It is still done in cases where something will be truly huge. It is also done in the name of speed where the data must be moved on and off the disk at speeds that are impractical for hardware. -- -- kensmith(a)rahul.net forging knowledge
From: Ken Smith on 7 Mar 2007 09:51 In article <158be$45eead75$4fe77f4$13972(a)DIALUPUSA.NET>, nonsense(a)unsettled.com <nonsense(a)unsettled.com> wrote: [....] >History teaches us that we are, unfortunately, reactive >instead of being pro-active when it comes to these things. > >The "think" signs should have been "think ahead" signs. The stock market tends to drive people in the direction of short term thinking. The need to keep the stock price up today reduces the chances that the needed extra computing power will be bought before the problem becomes very obvious. We are currently living in a world that has become brittle. -- -- kensmith(a)rahul.net forging knowledge
From: Ken Smith on 7 Mar 2007 10:18 In article <esmalk$8qk_001(a)s1012.apx1.sbo.ma.dialup.rcn.com>, <jmfbahciv(a)aol.com> wrote: >In article <esjvn9$1a4$4(a)blue.rahul.net>, > kensmith(a)green.rahul.net (Ken Smith) wrote: [....] >>If you know what you intend to write onto the tape, figure out what the >>checksum will be and then write the tape as you intend there is no extra >>effort needed. > >That does not give you a checksummed directory of the physical >tape you just made. All the handwaving and blustering you >are doing still does not satisfy the requirement. Yes it does. Imagine it step by step. (1) You calculate the checksum of what you intend to put on the tape. (2) You put exactly what you intend onto the tape (3) You calculate the checksum of what you have put on the tape. If the checksum at step (3) doesn't match the checksum at step (1), you haven't written what you intended onto the tape. I am really surprised that you can't see this. [....] >>If you intend to put the files onto the tape and can do so you can also >>figure out what the directory should look like before hand. This is so >>simple that it doesn't need further discussion. > >You still are not getting the fact that the directory of the tape >had to be on the tape--not a directory of the files on disk >soon to be copied to the tape. Why the devil can't you understand this!!!!!! Go back and look at what I wrote above. I have told you how to do it when you know what will end up on the tape. You were talking about tapes that will contain code to be sent to others. If you don't know what that tape will contain, you are not ready to make it. I also pointed out but did not cover that there is a method for tapes where the contents are not known before hand. The fact that you haven't been able to understand the simple case makes it nonuseful to get into that subject right now. >>The issue of what to do if you can't be sure about how much will really >>fit onto the tape is worthy of further discussion if you want to know how >>to solve that one. > >I know more about how to fit stuff on small tapes than you will ever >encounter. Tape fitting still has nothing to do with the requirement >of a directory of the tape prepended to the files we distributed >on that tape. The tail end of this is wrong in a way that I won't try to explain to you until you understand the simpler case. The start of it is evidence that haven't yet understood the simple case. [....] >>>You are talking about checksumming the files on the disk. That >>>was not the purpose of the directory file. This directory file >>>had to be done on the tape. >> >>Did you control what was written onto the tape or did some random >>generator determine it. If you controlled what went onto the tape, you >>knew before you wrote the first byte what all the bytes were going to be >>so the figuring out of the checksum was not really a problem. > >There would be too much of a time gap between getting the disk >checksums and saving the files to the tape. In addition, >a customer who restores a file can do a compare with the >file he has on his disk with what we actually put on the tape. So you now are suddenly talking about the more complex case. This has also been solved. It isn't rocket science. >It helps to know when (within the process of saving, distribution, >restoring, looking and using) a file was corrupted. So you didn't check your tapes before you sent them. (shutter) >> The problem >>is that you couldn't see how to make the checksum correct when the file >>that contained the checksum had to be included in the checksum. > >Since the contents of the directory file will always change (checksummed >file's checksum is the thing that will never be a constant), >there will never be an accurate directory of the tape. However, >no customer's system needed to use the directory-of-the-tape file's >checksum to verify their restores. This is wrong in two way. The checksum can in fact be put in place after all the data has been saved. The contents of the directory on the tape doesn't change once the tape is created and is ready to ship. >>A checksum is a simple sum where carried out of th etop of the word are >>discarded. For this reason you can take advantage of the observation >>that: >> >>A+B+C+D+E+F+G+0+0 == A+B+C+D+E+F+G+(-H)+H >> >>The checksum is not changed if two changes that cancel each other are >>made. > >This is not a very good sanity check. You didn't understand it did you? I may try again later on this. [....] >That is not how we used checksums when packaging our materials. >The program our customers used to get a checksum had to match >the program we used to get the checksum we reported. There is absolutely nothing in what I suggested that changes this. I will suggest you go back over the subject again. [...] >I'd never let you package our stuff. You are more interested >in fakery than in ways to assist customers to analyze stuff >that goes wrong. No, I am more interested in getting the right answer and you are more interested in defending a statement you made which is shown to be incorrect. I don't want the customer to have to analyze any extra wrong things so I wouldn't send them tapes with an obvious mistake on it. >Note that the obvious "solution" was to put the directory of the >tape in a saveset at the end of the tape. But that was unacceptable >because the customers did not need to have to read to the end >of a serious of save sets (which could involve more than one >tape) in order to "see" what was new and ID the beware files. The solution I gave is the right one. Just admit it. >It was also a goal, to minimize the number of times they had >to physical pass the tape on a reel over the heads in order >to restore what we shipped. They should only need one pass. Perhaps what you did contained another error that forced more than one since you brought the subject up. Assuming reel-to-reel tapes, you can command the tape into the read reverse mode to do the verify on the writing drive to do a verify of the contents. -- -- kensmith(a)rahul.net forging knowledge
From: Tony Lance on 7 Mar 2007 13:07 Big Bertha Thing book Cosmic Ray Series Possible Real World System Constructs http://web.onetel.com/~tonylance/book.html 6K Web Page Astrophysics net ring access site Newsgroup Reviews including soc.history.medieval Out of Copyright Illustrated Astronomy Book Sale From: David Hodgson Newsgroups: alt.astronomy Subject: Old Astronomy Books For Sale Date: Tue, 14 Sep 1999 From: Andy Mabbett Newsgroups: uk.sci.astronomy Subject: For sale: Old Astronomy books Date: Mon, 13 Sep 1999 From: (Oldbooks78) Newsgroups: sci.astro Subject: FS: Old Astronomy Books, 4 for 25 US$ Date: 26 Sep 1999 Big Bertha Thing toga What's a First Aid Tent? What's a toga party, in "Animal House" by National Lampoon? In "Mean Machine" starring Burt Reynolds, he said "If it worked once, it should work twice. Lets do it!" With the First Aid Tent, it worked twice, so it should work three times. The first two battles of cyberspace each started, when a first aid tent was set up. The first was set up on the OUSA Classical Particle conference. The second was set up on four conferences, in the pseudo Student Research Faculty. Needless to say both the conference and the faculty were subsequently closed down by order. "It's a tale to gladden the ears and to grow old listening to," said the giant in the "Chronicles of Thomas Covenant." by Stephen Donaldson. Tony Lance judemarie(a)bigberthathing.co.uk 01 June 1998 13:19:20 Message From: Mansour Abou Jaoudy Subject: Confused was Re: Big Bertha Thing repairs To: Tony Lance Cc: George Ho-Yow OUSA Controller group Hi Tony (& all) I haven't been much on line for some time, I come here to see loads of B.B.T. stuff in my mail box which i got no clue what to do with it. Is this a kind of joke taking so long. I recall some time ago couple of people wanted to be off the list but some how i still see their names on mmmmmm I see some light now ah no don't worry that is the monitor ON ;o) what makes me wonder, i see the OUSA Controller on the list, mmmmm i am sure she/he/they got something more important to do, or am i wrong. that leavs me with 3 options: a) This is all a joke and i just did not get it. b) This is some kind of a test to see how much mentally are we prepaired to take. c) You playing with fire. Now if it is "a" it is taking too long and people are getting upset (I myself one of them) I hope it is not "b", I re-checked your resume and you seem to me not the person who will do such a thing. you more into computers right. that leaves "c", well what shell i say, maybe we are lucky you got a 386 PC and not a PII 300 :o)) There is a conference about Programming and programmers, why don't you come by and share with us your expereince in this field, you seem you got lots of it and will be of good help. I have to say i am the mod of that conference but have not been there for more than 3 months, i feel like a stranger now ;o)) I have included every one in my reply (although i don't know who are the "group" ) and will try to keep it for this time only. I read your message about internet and did not know in which conference to reply to, well it sounds good. as i said it SOUNDS. my advice never trust anything free, specialy on the net. they have here some kind of a free telephone they say it costs you nothing and you can speak as much as you want, BUT while you are in conversation, every 2 minutes you get an advirt and you have to press a key for yes/no if you press the wrong key by misstake you might bet something home of �100 which you don't want at all. now my interesting part of the reply, The Internet ;o) here in Holland they will have access at the end of this year through the tv cable. and Holland is the best country in that way, since every single house got a tv cable that is handled by the cityhall. and they said the speed will be more than 10 times an ISDN line. now that is something interesting. OK enought talking now, back to work ;o) take care and keep your fingers off the fire Mansour
From: jmfbahciv on 8 Mar 2007 06:54
In article <esmj7c$bj2$1(a)blue.rahul.net>, kensmith(a)green.rahul.net (Ken Smith) wrote: >In article <esm9f6$8ss_002(a)s1012.apx1.sbo.ma.dialup.rcn.com>, > <jmfbahciv(a)aol.com> wrote: >>In article <esju3h$1a4$2(a)blue.rahul.net>, >> kensmith(a)green.rahul.net (Ken Smith) wrote: >[.....] >>>Having multiple disks connected to a single disk drive controller >>>electronics gives absolutely no advantage and a few disadvantages. >> >>I know that one can have multiple structures on one drive. Has >>the need of having one structure on multiple drives gone away? > >No, it hasn't gone away completely. There is a lot less need for logical >volumes to span multiple disks today. Is this because disk capacities are larger than most needs? With the habits of downloading music and videos, etc. won't there be another capacity problem fairly soon? > It is still done in cases where >something will be truly huge. It is also done in the name of speed where >the data must be moved on and off the disk at speeds that are impractical >for hardware. The last reason was valid in the olden days. JMF visited an insurance company site and saw a disk farm of [can't remember the number] hundreds, I think. He was awed because it was all one file. There was no way our products could deal with that kind of a data base. IBM knew how to handle those. /BAH |