Product Documentation

Database Administrator's Guide

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Server Memory Calculations

The considerations listed on this page apply to the non-SQL version of the FairCom Server.

The FairCom Server startup memory requirements can be reasonably approximated with the following equation:

Base line Memory =

Server EXE size + 1 MB +

Communications Library size (if applicable) +

Data cache (DAT_MEMORY) +

Index buffer (IDX_MEMORY) +

(900 bytes * Number of files (FILES)) +

(325 bytes * Maximum number of connections (CONNECTIONS)) +

(4 bytes * Maximum number of connections (CONNECTIONS)

* Maximum number of connections (CONNECTIONS)) +

(16000 bytes * Number of actual connections) +

(256 bytes per connection per file actually opened)

Note the following points:

  • DAT_MEMORY and IDX_MEMORY defaults vary between releases. For details, see the ctsrvr.cfg for your specific release, and the documentation.
  • PAGE_SIZE has changed by default over the various releases. V10-V11 default to 8K. V12 and later default to 32K.
  • FILES defaults to 1000.
  • CONNECTIONS default to 128.
  • IDX_MEMORY is the MAX of:

The following locking/transaction processing related items should be considered when approximating the FairCom Server dynamic memory requirements:

  • Each record locked consumes 24 bytes.

For transaction processing files only:

  • Each data record written consumes (record length + 42) bytes.
  • Each index operation consumes (key length + 42) bytes.

Note: Some operating systems offer virtual RAM (VRAM) which swaps data from memory to the hard drive. VRAM is usually automatically invoked if RAM gets full. Since data is being moved to and from the hard drive by VRAM, applications will often slow. If your system suddenly slows, examine this possible cause with your system administrator.