Tech Articles

RAM Details

Tech Articles ID    KB8022069
Status:    Published
Published date:    04/23/2015
Updated:    06/29/2015
Reported In:   MSC Nastran

Abstract (Question)

RAM Requirements:

  • More RAM is always better.
  • The RAM is used for the Nastran Solver and executive sections as well as for a computer's cache.
  • Nastran's memory allocation information is here.

Description (Answer)


Below is a chart of the memory layout and elapsed times for harware nodes with differing amounts of RAM. Jobs were run with mem=max which defaults to half the RAM and automatically partitions the amount of MEM for the solver and BPOOL area.


More RAM allows for a greater amount of BUFFPOOL. This increase may help significantly with SOL 400 and large FBS jobs.


Physical RAM can be determined with the free command. e.g.: 

[Node]# free
                        total         used      free    shared    buffers   cached
Mem:     132128660      8750260    123378400      0     316580    6457416
-/+ buffers/cache:      1976264    130152396
Swap:     10239992       72456      10167536

Memory Speed can be determined by logging on as root and issuing /usr/sbin/dmidecode which will print:

Memory Device
        Array Handle: 0x1000
        Error Information Handle: Not Provided
        Total Width: 72 bits
        Data Width: 64 bits
        Size: 16384 MB
        Form Factor: DIMM
        Set: None
        Locator: PROC  1 DIMM  1

        Bank Locator: Not Specified
        Type: DDR3
        Type Detail: Synchronous Registered (Buffered)
        Speed: 1866 MHz
        Manufacturer: HP
        Serial Number: Not Specified
        Asset Tag: Not Specified
        Part Number: 712383-081
        Rank: 2
        Configured Clock Speed: 1866 MHz

Nastran Memory is specified on the command line or in an RC file. e.g.:

     nast20141 job mem=24gb
     nast20141 job mem=max


  •     DMP jobs will require the amount specified by MEM for each process.
  •     DMP jobs with "mem=max" will use the maximum allowed / Ndmp for each job.








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