Sun GlassFish Enterprise Server 2.1 Performance Tuning Guide

File Transmission

When File Transmission is enabled, the server caches open file descriptors for files in the file cache, rather than the file contents. Also, the distinction normally made between small, medium, and large files no longer applies since only the open file descriptor is being cached.

By default, File Transmission is enabled on Windows, and disabled on UNIX. On UNIX, only enable File Transmission for platforms that have the requisite native OS support: HP-UX and AIX. Don’t enable it for other UNIX/Linux platforms.