What is the maximum number of RealPort devices my Unix system will support?

The purpose of this document is to give administrators of various Unix operating systems an idea of just how many RealPort devices they can have per server running the Digi RealPort driver. It is also important to understand that although the RealPort driver may support X number of PortServer/EtherLite units which creates X number of ports, the amount of memory on the server is a limitation as well. In other words, a Unix server which has many devices running on it will need sufficient memory to handle those devices.

The Digi Device Server/Terminal Server family comes in a number of different port densities. The number of ports per unit varies depending on the model, but generally speaking this number is 1, 2, 4, 8, 16, 32, or 64 ports per Device/Terminal Server. Keep these numbers in mind when determining how many total ports YOUR Unix server running RealPort will have. Since 64 ports is the maximum number of ports per Terminal Server, this is the number used in the examples below for calculating the maximum number of ports per Unix operating system.

HPUX:

• 500 RealPort Servers at 64 ports each = 32000 ports maximum.

  AIX:

• 500 RealPort Servers at 64 ports each = 32000 ports maximum.

  SCO Unixware:

• 500 RealPort Servers at 64 ports each = 32000 ports maximum.

  Solaris Sparc and x86:

• 1016 RealPort Servers at 64 ports each = 65024 ports maximum.

  Tru64 Unix 4.x and 5.x:

• 1016 RealPort Servers at 64 ports each = 65024 ports maximum.

  Linux:

• No apparent limitation exists in the driver. The only limit exists in the kernel, which depends on the version of the kernel, as to how many RealPort Servers we can support. At minimum, we support 255 RealPort Servers at 64 ports each = 16320 minimum.

  SCO Openserver:

• To find out the maximum number of RealPort services/ports for SCO, you first have to find out how many major numbers are already in use since each instance of the RealPort daemon uses a major number. Here are the steps to make this calculation:

   

  • # /etc/conf/cf.d/majorsinuse |wc -w
    152
• Subtract the result of the previous step (152 in our example) from 255 (total number of majors in SCO) to get the maximum number of RealPort servers you can have for that system. A typical result for a newly installed SCO Openserver server would be around 120-130 majors available.
• Multiply the number of available majors from the previous step by 64 for the maximum number of ports your SCO Openserver system could support.