🚀 go-pugleaf

[note 1:  i have added comp.windows.x to the newsgroups lines.  i
think both groups would be interested in this topic]

[note 2:  i realize that although the subject line says "X-term v.
PCs..." that most of the actual discussion has been on the pros and
cons of MIS departments.  for the most part, this is irrelevant
to me, the company i work at, and our customers. ]




i am very interest in subject of X terminals vs. PC's running X vs.
diskless workstations vs. disk based workstations and when to use each
of these systems.

over the next year or so we are going to be replacing most of the
computers on our (nonstandard and slow) lan with something that will
run X.  we are also going to have to start selling systems that run X
and our customers are very interested in low-cost systems that have
reasonably high performance.  (i.e. even if system XYZ has great bang
for the bug and super performance, they wont want it if it costs over
$20k per seat.  if it gives even "ok" performance for around $3-5k per
seat, they will jump at it.)

a little background might help.  we sell a cad package that's main
claim to fame is that we have large processing and picture creation
programs that let our customer put a little bit of information in and
get out finished cad drawings.  most of our customers use small lan's
(less than 5 seats), but networking is very important to them.  our
customers will typically spend equal amounts of time in the cpu & disk
bound programs and our graphics package, although any given person may
spend most of his/her time in only on only one of these two programs.

what i have been thinking about recommending using is a "large" main
cpu/disk server that will run the cpu/disk bound programs.  the
graphics package i am not really sure where they should run.  would X
terminals give good enough graphics performance, or would it require a
workstation of some sort?  the second question is which is better, x
terminals or pc's running X and discless vs disc based workstations?


as i see it, each system has advantages and disadvantages. 

X terminals:

  Advantages:

    * "cheap", possibly the least expensive of all.

    * everything you need to run X is already put together for you.
      you dont have to add lan cards, or install operating systems

    * all of the advantages of using a central cpu server:

      * economy of scale. it is usually cheaper to by one 4meg
        board than 4 1meg boards, and one 300 meg disc than 5 60meg
        disc's.

      * one point system maintenance.  only one system to back up.
        only one system to upgrade with a new operating system.  if
        your central system is a multiprocessor, you can add a cpu and
        everyone benefits.  if you add more memory, everyone benefits

      * shared resources.  only one copy of the operating system,
        utilities, and application programs on disc.  only one copy of
        the operating system taking up memory (as opposed to having to
        buy memory for each workstation to run an operating system).
        application programs that are being used by more than one
        person are shared in memory rather than being duplicated on
        each workstation.  since X programs tend to be large, this is
        more important than if you are running different copies of "vi".

    * one of the advantages of decentralized computing:

      * you can add "graphics power" by adding additional X terminals


  Disadvantages:

    * can you upgrade the terminal to use X11R4 (or whatever).  does
      this make a difference?

    * everything that goes to the screen must go over the lan.  highly
      graphically oriented programs may use up a lot of the lan's
      bandwidth.

    * all of the disadvantages of using a central cpu server:

      * economy of location.  a central computer may be faster and
        cheaper, but it cost time and resources to transmit
        information to and from it.  the central computer may be able
        to figure out what to draw in half the time, but it make take
        longer to get that information to the screen.

      * response time may be inconsistent.  if lots of people are
        trying to do things on the central server, it will take longer
        to get things done.

      * if the main system goes down, everyone stops working.
        personally, i dont really agree with this argument.  if the
        lan goes down, everyone stops working too.  and the bigger/more
        complicated you make each workstation, the more likely it is
        to go down.  you may end up with less _total_ downtime by
        using a central server.  i generally dont consider this to be
        a very important consideration.

      * you can't add cpu power without upgrading the "entire system".
        that is, if you use distributed computing, you and add cpu
        power by just adding another workstation and you can give one
        person a much faster workstation and give the old workstation
        to someone else.  of course, there is still the problem of
        what to do when you need to upgrade your lan, so in a sense
        you always have an "entire system" that may need upgrading...



PC's running X windows
  
  Advantages:

    * "cheap", possibly cheaper than X terminals...?

    * you can run other things besides X, such as dos programs.

    * people may already have PC's.  (this is not the case for us)

    * upgrades are definitely possible.  both with newer/faster
      hardware and with newer software.

    * for X programs that run on the central server, all of the
      advantages of centralized computing.

    * for programs that run under dos, all the advantages of
      decentralized computing.  assuming of course that you can use
      the lan for dos.  i am not sure how many dos network will work
      on the same lan as unix.  pc-nfs may be a solution.

  Disadvantages:

    * you have to put things together.  making sure the X software
      works with the graphics card, lan card and the server.  this may
      be a _major_ problem, depending on how much you know about dos,
      dos related hardware and how many different combinations you
      have. 

    * like the X terminal, everything that goes to the screen must go
      over the lan.  highly graphically oriented programs may use up a
      lot of the lan's bandwidth.

    * for X programs that run on the central server, all of the
      disadvantages of centralized computing.

    * for programs that run under dos, all of the disadvantages of
      decentralized computing.



diskless workstations
  
  Advantages:

    * cheaper than disk based workstations. 

    * you can run other things besides X, such as unix programs.

    * upgrades are almost always possible.  both with newer/faster
      hardware and with newer software.

    * X programs that do a lot of screen i/o can be run locally.  but
      if you run X programs that use a lot of disc i/o locally, you
      can bog down the network.  if your program uses both disk i/o
      and graphics, it may be hard to tell where to run them.  (our
      programs usually do one or the other, but not both)

    * for X programs that run on the central server, all of the
      advantages of centralized computing.

    * for programs that run run locally, some the advantages of
      decentralized computing.  the main difference is that disc i/o
      must still go through the central server.

  Disadvantages:

    * swap space for each workstation must be reserved on the main
      server.

    * the absolute minimum amount of memory need on a workstation is
      probably around 3 meg, for the operating system and x server.
      this doesnt include the mrmory for actually doing real work.
      you will probably need a minimum of 1 meg for each x program
      that you plan to run, including xterms and such.  our programs
      are probably going to require about 3-5meg.

      basically, you are looking at 8-16meg of memory for a diskless
      workstation, a lot of it could have been shared by multiple
      users if the programs (and operating system) were run on the
      main server.



disk based workstations
  
  Advantages:

    * this configuration will probably give you the most consistent
      response time.

    * you can run other things besides X, such as unix programs.

    * upgrades are almost always possible.  both with newer/faster
      hardware and with newer software.

    * X programs that do a lot of screen i/o can be run locally.

    * programs that need to do disc i/o that arent to shared files can
      do the disk i/o locally.  

    * for X programs that run on the central server, all of the
      advantages of centralized computing.

    * for programs that run run locally, most the advantages of
      decentralized computing.  

  Disadvantages:

    * on the surface, this appears to be the most expensive option.

    * memory requirements are going to be about the same as a discless
      workstation, and again, a lot of this memory could have been
      shared if things were run on the main server.



please let me know of any advantages or disadvantages that i have
forgotten.  also please point out anything you disagree with.
i realize that many of pros/cons are really two sides of the same
coin.  arguments in the form of "well, the pro's outweigh the cons, so
the cons are irrelevant" probably wont help much.  i am much more
interested in _why_ you think the pro's outweigh the cons. 


anyway, my _real_ concerns with each option are:

X terminals:
  * are they really the cheapest option?
  * are they really fast enough to do useful work?
  * am i going to be stuck two years from now when X11R6 comes out and
    my X terminal is X11R3 based?

pc's running X:
   * compatibility between all of the parts is a real concern.  has
     anyone actually put together a good reliable configuration?  if
     you have, please let me know.
   * will pc-nfs really work well to network the dos programs?  does
     anyone know where i can get a copy of pc-nfs?

diskless workstations:
   * will they bog down the network so much that to make them useless?
   * are they really going to be any cheaper than disc based
     workstations

disk based workstations:
   * could this really be the cheapest system when everything is
     considered? 


please mail or post your replies.  i will try to summarize the mail
responses that i get.  


thanks much for any help...


-wayne