PSF (/var/psf/segments)

As described in Print jobs and print files, PSF Input Manager segments AFP files so printing can start before a job completes ripping. The smaller the segments, the faster PSF starts printing the job. However, if the pieces get too small, there will be too many files and too much disk thrashing. If PSF has to open a new file for each page that can slow things down significantly.

The default setting of 5000KB for each segment can be raised to reduce the disk I/O associated with reading and writing data to the /var/psf/segments file system; however, the default setting usually works well with most AFP production applications.

The InfoPrint Manager SMIT Customize the Input Manager panel (InfoPrint Manager → Miscellaneous → Customize the Input Manager) lets you change the default segment size. The segment size parameter determines the maximum size of any temporary file created by the Input Manager component of InfoPrint Manager that is stored in /var/psf/segments. This parameter should only be adjusted when there is a problem with throughput.

Since there are so many small files stored in /var/psf/segments, you might think you should change the fragment size of the file system to allow for better space utilization. However, for better performance, it is best to set the fragmentation size at its highest value of 4096 bytes because a smaller size might increase disk I/O operations.

By default, segments are deleted when they are no longer needed by PSF. You can specify no with the delete-segment-list job attribute to retain the segments. You might want to do this if you are reprinting the job. When segments are retained, Input Manager automatically manages the space in /var/psf/segments. By default, fifty percent of the space will be allotted for retained segments. The Customize the Input Manager SMIT panel can also be used to change this value. A higher value will cause Input Manager to retain more print data in the system to extend the range of re-start and rerun job management functions. However, a higher value might cause printer clutching since there will be less room for the printing jobs segments.