Conference csc32::consolemanager

1078.0. "Old Decserver's hang PCM" by 60600::DONNELLY () Thu Nov 02 1995 19:26

    Hello All,
    
       I have spent a little time setting up a Console manager
    configuration here in the CSC and have found an interesting way to
    reproduce many of the customers problems and a number of the problems that 
    other people have documented in this notesfile. 
    
      USE a Decserver 200 or similar old style DECserver to connect up your 
    systems! When you use one of these on a loaded network you get 
    a much worse response than you get with a newer DECserver in the same 
    position. This really upsets Console manager (V1.6 ECO 1) which just 
    doesn't seem to cope with delays talking to DECserver ports! You then
    see Line Controllers going off into limbo which has a knock on effect
    on process's that use these. 
    
     Another point that I have observed by experimenting. When You connect
    a system that produces large amounts of console date (a system running
    Decnet-OSi is a good example here) you start to get Overun error's on
    the port. Once again this seems to upset Console manager no end (and I
    don't know why) Putting a more recent DECserver in place of the older
    one fixes the problem. I guess the newer terminal servers have bigger
    buffers on each port.
    
       Conclusions:-  Console Manager is not a very HARD product. In
    perfect conditions it works fine but in anything less than perfect
    conditions it hangs up left right and centre and can only be fixed by
    constantly shutting it down and restarting it. Given it's current
    status it's not likely to become HARDENED. Perhaps for starters someone
    should revisit the SPD and start dropping the older DECservers of the
    list as they expose all the weakness's in the product. Unfourtunatley
    PCM acts as a retirement home for old DECservers for a lot of
    customers!!
    
       Has anyone else tested PCM against an old decserver latley?
    
    Cheers,
    
    Steve Donnelly
    SYDNEY CSC

    Yes, lots of sites still use DECServer 200's. As far as LAT is
    concerned, PCM is by the book in terms of the way it handles LAT
    connections etc.  There is even reconnect code that kicks in if a
    server connection is lost and it will attempt to reopen the line
    every 150 seconds. I have run into numerous problems with these servers
    being booted against older versions of the decserver software however.
    
    
    I do agree that there are much better choices for a server though
    especially if character throughput is an issue. DECServer 200's are
    slow and just not up to the job for a lot of sites that are using
    them.
    
    One thing that isn't mentioned in the docs is that the SYSGEN params
    TTY_ALTYPAHD and TTY_ALTALARM should be adjusted on the the PCM engine.
    With VCS it was suggested to set these to 1000 and 320 respectively and
    this seems to work well with PCM too. If you increase them maintain the
    3 to 1 ratio.
    
    Regards,
       Dan

    Hello Dan,
    
       Thanks for the tip. Now I have a understanding of the performance -
    or lack of it that the DS200 offers I'll try your idea to improve it.
    
    Cheers,
    
    Stev