FAT32 Installable File System Driver

Wikis > FAT32 Installable File System Driver


Please read the ReadMe before installing and using this software.

Submitting tickets

Reporting bugs and requesting new features is done through the ticket system. You can view existing tickets, add comments to them and create new tickets using the corresponding buttons at the top of every page. If you want to submit a new bug or request a feature, please use the Search function first to make sure there is no ticket for the same problem already created.

Installation notes

Prior to ArcaOS 5.0.3, ArcaOS included the Netlabs FAT32 driver. The following caution applies to all versions of ArcaOS prior to 5.0.3, and any subsequent versions where the Netlabs driver has been installed.

THE ARCA NOAE FAT32 DRIVER IS NOT AN UPGRADE TO THE NETLABS DRIVER. Switching from the Netlabs FAT32 driver to the Arca Noae FAT32 driver using the WarpIN installer requires first uninstalling the Netlabs driver, and then installing the Arca Noae driver. No reboot is necessary in between these two operations, however, NOTE THAT THE NETLABS FAT32 DRIVER HAS BEEN KNOWN TO REMOVE CRITICAL CONFIG.SYS ENTRIES UPON UNINSTALLING IT. There are two workarounds to this situation:

  1. When selecting the Netlabs FAT32 driver for removal, carefully review the CONFIG.SYS changes listed, and deselect the removal of the PATH= and LIBPATH= entries. Manually edit CONFIG.SYS after removal to ensure that these statements are correct.
  2. Alternatively, restore CONFIG.SYS from a backup copy after uninstalling the Netlabs FAT32 driver and before installing the Arca Noae FAT32 driver. Again, you should review CONFIG.SYS prior to rebooting the system.

When uninstalling, be sure to allow WarpIN to unlock any files in use so that they may be properly deleted from the system. Be sure that no FAT32-formatted devices are active until after the reboot following a successful installation of the Arca Noae FAT32 driver.

Version numbers

The initial release of the Arca Noae FAT32 driver was version 5.0.0. This major version number was chosen specifically as the initial release version for two reasons:

  1. it coincides with the major revision number of ArcaOS (5); and
  2. it is sufficiently offset from the Netlabs version series so as to avoid confusion between the two different drivers.

Differences between Arca Noae and Netlabs drivers

While both drivers share a common ancestor, the Netlabs FAT32 driver has been expanded to included non-FAT32 filesystem support, including replacing the OS/2 kernel’s built-in FAT12 and FAT16 support, as well as support for VFAT and exFAT. In addition, support has been added to the Netlabs driver for mounting filesystem images. Arca Noae’s approach is fundamentally different, in that we view the FAT32 filesystem driver to be just that: an installable filesystem driver to support FAT32 volumes; nothing more, nothing less. Thus, excess has been removed from the Arca Noae FAT32 driver. Great effort has been made to ensure that the Arca Noae FAT32 driver contains no potentially patent-infringing code.

Both drivers support formatting and disk checking of FAT32 volumes, as well as maintaining a CHKDSK log akin to the one produced by the HPFS CHKDSK.

Some command line utilities (F32STAT.EXE, as an example) are not included with the Arca Noae FAT32 driver distribution. Other utilities (CHKDSK, in the case of F32STAT) should provide reasonable functionality without duplication. It should also not be expected that these utilities, taken from a Netlabs FAT32 distribution, will work at all or will work without negative effects with the Arca Noae FAT32 driver.

The Arca Noae FAT32 driver includes fully re-written documentation and support by Arca Noae. The Netlabs driver includes additional material which may be of interest to developers.

Both drivers are open source, licensed under the same LGPL v2.1. Certain components of the IBM Developer Connection Device Driver Kit for OS/2 (the “DDK”) are required in order to build the FAT32 driver. These components are not part of the Arca Noae FAT32 repository, as they are not publicly available nor legally redisttributable in source form. More information concerning the DDK may be found at EDM/2. Anyone wishing to build the FAT32 driver from source must have the necessary DDK headers.

Access to source code

The source code for the Arca Noae FAT32 driver may be accessed via svn:


Partitioned vs Unpartitioned media

Due to limitations of OS/2, unpartitioned media of sizes large enough to support FAT32 (8MB, minimum) will not be recognized by the operating system. Such media is considered “large floppy” and lacks a partition table. To make such devices (typically USB sticks) usable by OS/2, it is necessary to copy any data from the media to something else, partition and format it, and then restore the data to the newly-partitioned file system.

For specific instructions on how to properly prepare USB sticks for use with OS/2 using ArcaOS, see this wiki page.

Known issues


Reformatting an existing FAT16 volume as FAT32 requires an intermediate step as a workaround. To make this change, first reformat the volume as HPFS or JFS, and then reformat as FAT32. This is due to the design of OS/2’s FORMAT.COM and not a defect or shortcoming of the FAT32 driver or its utility DLL. Arca Noae is looking at long term solutions to this issue.

Disk checking may not be able to repair all possible errors to the FAT32 filesystem (just as disk checking may not be able to repair all possible errors to any other filesystem).

Changing codepages requires also changing the FAT32 codepage, separately, via the CACHEF32 utility. This is a limitation of the driver architecture. The filesystem driver is not otherwise notified of a change in codepage for a given session.

There is currently no known OS/2 utility to defragment FAT32 volumes. To work around this, Arca Noae recommends that for local volumes located on mechanical media which seem to be badly fragmented (e.g., poor read/write performance), files should be copied off of the volume(s), the volume(s) should be reformatted, and the files may then be copied back. Defragmenting non-mechanical media (SSD or USB-attached flash drives) is unnecessary and will cause additional wear to the memory in these devices. It is not recommended to defragment such media.

Extended attribute (EA) handling on FAT32 volumes differs greatly from native OS/2 filesystems (HPFS and JFS) and from FAT12 and FAT16. As a result, other anomalous behavior may be observed when using different applications which may be sensitive to extended attributes. Arca Noae does not recommend the use of EAs on FAT32 volumes. Enable this feature with care.

The command line help for FAT32 messages (e.g., “help F32101”) fails when using a 4OS2 shell prior to 3.10. 4OS2 tries to open its internal help file instead. This was a 4OS2 limitation.

This entry last updated: by Lewis Rosenthal