Invisible Software

About Network File Handles


This technical support note briefly explains what file handles are, and how to configure the server and redirector so that you have enough of them. This information applies to the DOS and Windows 3.X version of Invisible LAN.

In DOS when I open a file on a stand alone machine there is only one file table. It's very simple for DOS to keep track of what files are opened.

In a network, when a workstation opens a file on another machine, both machines need to keep track of what files are opened. The workstation uses a REDIRECTOR file handle, and the server uses a SERVER file handle.

In DOS the file table has a maximum limit of 255 files (that's DOS for you). The server can add to the size of this table if the PRIVATE FILES option is turned on. The private file table can be up to 1000 files.

Here's where it can get tricky. Let's say I have a program that opens 100 files. I want to run it on five workstations at the same time. The server needs to know exactly who has what open, so the files are referenced five times even though they are the same files. That is a total of 500 file handles the server needs to keep track of. Since DOS's file table is only 255 files, you need the private files option turned on.

Here is how you configure the server and redirector.




PRIVATE FILES=Y (This creates a file table larger than DOS's 255)

FILES=500 (This is the number of files open on SERVER)




NOTE: Windows will not run on a machine with the private files option turned on.

The CONFIG.SYS "FILES" statement plus the REDIRECTOR "OPEN FILES" can't exceed 255. On the workstation just set the redirector to the maximum files the program opens. Give the CONFIG.SYS the rest of the 255.

The more file handles you allocate, the more RAM you use.


Notices: Copyright 1995 by Invisible Software, Inc. Invisible Software and InvisibleLAN are trademarks of Invisible Software, Inc. Other trademarks are the property of their respective holders.

This document was prepared on 06/06/95, and was believed to be accurate as of that date. Procedures, specifications, and compatibility may change without notice, and therefore this document may be out-of-date and/or inapplicable to current product versions. Invisible Software provides this document "AS IS" and without warranty of any kind. Under no circumstances shall this document be construed as creating or expanding any warranty of product performance.


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