McIDAS-X uses shared memory for frame allocation. On some operating systems, the shared memory facility is activated by default and has a sufficient maximum segment size for most McIDAS-X sessions. However, this is not always true for Linux and Mac OS X systems. The system administrator must check and, if necessary, force the kernel to activate the shared memory system at boot time and set the maximum segment size to 512 MB or greater the first time McIDAS-X is installed on a Linux or Mac OS X workstation.
The McIDAS Users' Group uses the following settings on Linux and Mac OS X.Red Hat Enterprise Linux
Check for lines similar to the two below. If the lines do not exist then add them to the end of the file. If the lines exist and are set to the value below (536870912) or greater you can leave them as is. If the lines exist but are set to a smaller value, change the values to those below.
|kernel.shmmax = 536870912
kernel.shmall = 536870912
Run the following command from the Unix prompt.
Type: /sbin/sysctl -p
Mac OS X
As user 'root', create the file /etc/sysctl.conf and add lines similar to those below (which are an example that sets the maximum shared memory segment size to 512 MB).
After making these changes, the system will need to be rebooted for the changes to take effect.
Updated February 2017