what types of long term data storage are used by modern mainframes?

Discussion in 'NZ Computing' started by Bling-Bling, Jun 11, 2005.

  1. I thought a "statement" was a legal document. Once a bank puts something
    on your statement, that means the transaction has formally been
    processed.
     
    Lawrence D’Oliveiro, Jun 26, 2005
    #41
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  2. Bling-Bling

    Bling-Bling Guest

    Depending on whether you are talking about the actual real
    monthly/weekly/daily statements or the slips of paper that you can get out
    of an ATM.


    Bling Bling
     
    Bling-Bling, Jun 26, 2005
    #42
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  3. Bling-Bling

    Sc00ter Guest

    Don't forget about the footwear polishing.
     
    Sc00ter, Jun 27, 2005
    #43
  4. ... and a really big one. Some of our removeable cartridges (for PDP/VAX)
    were 40 MB IIRC and about haf the size of a bucket. Boy could it get the
    place rocking :)


    Bruce


    -------------------------------------
    The power of accurate observation is commonly called cynicism by those who have not got it.
    - George Bernard Shaw
    Cynic, n: a blackguard whose faulty vision sees things as they are, not as they ought to be.
    - Ambrose Bierce

    Caution ===== followups may have been changed to relevant groups
    (if there were any)
     
    Bruce Sinclair, Jun 27, 2005
    #44
  5. Like a visa card transaction ? ... or a cheque deposit ? :)
    IME, those can be reversed ... as can bank fees :)

    Bruce


    -------------------------------------
    The power of accurate observation is commonly called cynicism by those who have not got it.
    - George Bernard Shaw
    Cynic, n: a blackguard whose faulty vision sees things as they are, not as they ought to be.
    - Ambrose Bierce

    Caution ===== followups may have been changed to relevant groups
    (if there were any)
     
    Bruce Sinclair, Jun 27, 2005
    #45
  6. Bling-Bling

    Jerry Guest

    Some years ago I worked in a plant that manufactured disk drives. Some
    tech on the line was having a problem and had taken a drive apart a few
    times, finally trying to get it running but leaving the shroud (a metal
    pan that the disk pack fit in) off the machine. It was a 30MB removable
    pack, equivalent to an IBM 2314. To move the heads there is a big coil
    moving through a huge magnet. Involved in the circuit is a small
    magnetized rod moving in a coil that senses the speed and direction of
    the head assembly. We have 20 heads, some considerable amount of stuff
    moving here. Well, he managed to get the taco (the sensor coil)
    connected backwards. It was one of the most spectacular disk disasters
    I've seen. The carriage assembly starts to move, and it is sensed that
    it is going backwards, so the circuitry applies more current. The head
    assembly finally crashes into the end stop at full speed and bounces.
    On the bounce the sensor detects a change of direction, and so tries to
    stop it, applying full current in the other direction. Now we get the
    heads heading back in the hole, and off the pack at considerable
    velocity, until they hit that end stop, and the whole thing starts over
    again. All of the heads are sitting on 14 inch platters spinning at
    2400 RPM and soon bits of head start flying, the steel parts of the
    carriage dig into the pack, and since there is no shroud to catch the
    mess, things are leaving the machine at some considerable velocity.
    There were a couple of brave attempts to approach and unplug or switch
    the thing off, but the flying shrapnel soon ended this efforts. It
    sounded amazing, like a very fast machine gun. Finally the power
    transistors gave up in a puff of smoke, any bits that could part
    company with the machine did so and someone was able to hit the power
    switch.
     
    Jerry, Jun 27, 2005
    #46
  7. Its processed overnight usuallu
    This should tell you it is not a realtime system
     
    FreedomChooser, Jun 27, 2005
    #47

  8. A lot of varience
    But for most cases when I get paid say it appears the next day in my
    bank account after the transaction was done
    "Overnight" being the term

    Cheque clearances an interesting one
    There is a legal requirement for clerance times
    Trustbank used to clear a percentage each clearance day until the
    period expired
    Other banks wait the full period before making any funds available
     
    FreedomChooser, Jun 27, 2005
    #48
  9. A full realtime system requires more expensive hardware
    Whereas logially most of the banks get the processing done overnight
    when the system is not being used - its called efficiency
     
    FreedomChooser, Jun 27, 2005
    #49
  10. Bling-Bling

    Chris Hope Guest

    I had a funny one last week. I deposited an international cheque into my
    account with a value of something like $166.59 and they made 59c of
    that available funds. Must be some rounding thing or other...
     
    Chris Hope, Jun 27, 2005
    #50
  11. Bling-Bling

    Bok Guest

    That's a good story, made me laugh. I can relate to that having worked
    with that type of disk technology. Reminds me of a similar (less
    spectacular) incident were a disk drive was delivered to the field with
    the 'linear motor' leads connected in reverse. This gave rise to the
    opposite behaviour: during the power on cycle when the heads were
    supposed to load the carriage assembly was driven backwards into the
    'linear motor'. Fortunately, the head load failure was detected,
    terminating the power up cycle with a 'fault light'. No damage was
    incurred, once the leads were reversed it powered up successfully. We
    were surprised actually, since it obviously can't have been tested in
    the factory (although it's possible some *prankster* got to it after
    testing - who knows).
     
    Bok, Jun 27, 2005
    #51
  12. Bling-Bling

    Bok Guest

    The smallest removable 'Disk pack' media I can remember working with was
    around 60MB (Burroughs 206 pack), an older vintage different style had
    a capacity around 87Mb. Each cabinet had two drawers. The smaller
    machines had removable cartridges - I've no idea what size they were. I
    can also recall a 'head per track' (non movable) style of fixed disk
    that had around 20MB capacity (access time around 5ms - no seek required).
     
    Bok, Jun 27, 2005
    #52
  13. Bling-Bling

    Bok Guest

    Hope you took something useful from the TOI Murray. I was up the front a
    few times blabbing on about one thing or another ;-(
     
    Bok, Jun 27, 2005
    #53
  14. Bling-Bling

    Murray Symon Guest

    Yes, thanks, I was suitably impressed.
     
    Murray Symon, Jun 27, 2005
    #54
  15. Bling-Bling

    Jerry Guest

    The 60MB were probably a double density version of the IBM 2314. The
    2314 used a hydraulic unit to move the heads, most copies used a voice
    coil. We made a 60MB version for Burroughs, 20 heads, 408 cylinders 14
    inch platters. We even made a 120 MB version of the same drive,
    different pack and heads, still 408 cylinders but double the R/W
    Frequency. We only sold those to Burrougs and Univac. I don't think it
    was a Burroughs drive that self destructed in the plant, but it was the
    same style and could have been.

    I worked on a lot of IBM drives after Century Data. The hydraulic unit
    added the prospect of squirting oil to the fun of working on disk
    drives. If you got a fun problem, a stream of oil might hit the
    ceiling. Part of PM involved changing the oily rag on the deck plate.
     
    Jerry, Jun 27, 2005
    #55
  16. Bling-Bling

    Bok Guest

    Interesting! What was the name of the company you worked for? All the
    removable 'disk pack' units I worked with had 'voice coil' head carriage
    motors. The 206 (removable) and 207 (fixed) disk drives came from a
    factory in Winnipeg (CA); Burroughs may have acquired the manufacturer
    as they tended to in those days. The other removable drives from that
    era were the 'dual density' 225 drive (87MB formatted capacity) and 235
    quad density (~160MB formatted). These drives also had a B-94xx-nn
    designation, that I can't recall. The 225 drive had around 20 heads, 40n
    cylinders and 60 x (180byte [1]) sectors per track IIRC. The next
    generation disks Burroughs/Unisys used were made by Memorex.
     
    Bok, Jun 27, 2005
    #56
  17. Bling-Bling

    Bling-Bling Guest

    Long term data storage devices as used by modern mainframes today - how
    would you describe them?


    Bling Bling
     
    Bling-Bling, Jun 27, 2005
    #57
  18. Bling-Bling

    Jerry Guest

    The company was Century Data in Anaheim California. They were later
    taken over by Calcomp.

    The removable packs of the time were ripped off from IBM's 2314. The
    2314 used a hydraulic unit to move the heads, and then a pawn physically
    locked or detented the carriage. Most other manufacturers (the
    exception was an outfit called Marshall) used a voice coil, and an
    electrical detent. With some temperature compensation the track density
    could go to 200 TPI, up from 100. Memorex used a voice coil, but kept
    the mechanical detent, which limited it to the IBM 204 tracks.

    As far as I know Century Data (or Calcomp) was the only manufacturer
    other than IBM to make the drives in a pizza oven configuration (2
    drives in drawers), all the others made washing machine drives.

    20 heads, the bottom platter was a dummy, a little bigger than the rest
    and had the index and sector notches cut in it. IBM devices didn't use
    hard sectors, you could write variable length and even multiple track
    records. Any other manufacturer could specify however many sectors they
    wanted. Your 206 and 225 disks sound like ones that we made for
    Burroughs.

    I worked for Memorex for a while after that, but not in the plant. I
    think at one time or another I've worked on just about everybodies
    version of the 2314, and the 3330 after that. The next generation was
    still removable, 20 heads but one was a servo head. IBMs maximum
    capacity was about 200MB, the technology was stretched to about 300 MB
    unformatted by some manufacturers, like Memorex or Control Data. Poor
    Century Data kind of collapsed, and Calcomp dumped most of their
    acquisitions and went back to what they did best, making plotters

    Thinking about it, the exploding drive in the pland couldn't have been a
    Burroughs drive, it was a washing machine style. All Burroughs, as well
    as Univacs were pizza ovens.
     
    Jerry, Jun 28, 2005
    #58
  19. I was trying to interpret "pawn", and kept having visions of some
    hapless underpaid staff member whose job it was to brave the hazards of
    taming a recalcitrant disk drive!

    I think you mean "pawl" ...
     
    Lawrence D¹Oliveiro, Jun 28, 2005
    #59
  20. (Bruce Sinclair)
    Oh, certainly, but the reversals are additional transactions and require
    additional statement entries, which will also turn up on your
    statements. Once something appears on your statement, it can't un-appear.
     
    Lawrence D¹Oliveiro, Jun 28, 2005
    #60
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