HPFS.IFS

HPFS Installable File System driver for OS/2

The High Performance File System (HPFS) was introduced with OS/2 Version 1.2 in 1989.

CONFIG.SYS Statements
This command installs the High Performance File System. Without this command you can't access any HPFS formatted drives. IFS=C:\OS2\HPFS.IFS

NOTE: You can have multiple partitions, they will all be serviced by the same cache, so you may have 2 HPFS and 3 FAT partitions for example. For purposes of the table above, "active" and "passive" are descriptors for the way a cache is used. If it is seldom used, it is "passive." If a lot of disk intensive I/O occurs with the cache, it is "active."

NOTE: HPFS is more efficient than FAT, you should therefore attempt to transfer all the most frequently used applications to an HPFS drive, and also locate your SWAPPER.DAT on an HPFS drive. This will mean that HPFS is "active", and FAT "passive"

NOTE: Lazy write is on by default. If you want lazy write off, see the RUN=C:\OS2\CACHE.EXE command later in this file.

Tip: /C will only run CHKDSK if the file system is dirty (new); /AuToChEcK (case-sensitive!!!) will make CHKDSK process locked drives (undocumented). You can speed up checking volumes situated on separate physical drives by using something like IFS=C:\OS2\HPFS.IFS /CACHE:2048 /CRECL:64 /AUTOCHECK:C and then running the CHKDSK's in parallel for each physical drive: start CHKDSK D: /F /AuToChEcK start CHKDSK E: /F /AuToChEcK and so on. Some have reported performance improvements of 250%.

NOTE: If you place a plus sign (+) in front of any drive letter, the drive will be checked every time the system starts, even if shut down properly.

WARNING: If you don't include the AUTOCHECK parameter in this command, the system will not boot.

Tips

 * If you are using only FAT partitions, then you should REM this IFS statement and save yourself some RAM. How much? I've seen figures from 130k to 500k, but the HPFS.IFS file is 136k in size.
 * If you have drive partitions larger than 80MB, then HPFS should give you better performance than FAT. On partitions of less than 80MB, most authorities indicate that there is only a small performance difference between HPFS and FAT. Consider the following when comparing the relative merits of the HPFS versus FAT: On large partitions of identical size, the HPFS will generally give you about 15% more space and improve performance by about 28%.
 * Use HPFS386.IFS if you have a license. It brings an significant performance boost into your system.
 * For analysing HPFS formatted drives there is the FREE Tool DFsee by Jan van Wijk, available at http://www.fsys.demon.nl. DFSee can also undelete files, fdisk and much more.
 * For undeleting files on HPFS drives use the IBM EWS Tool File Phoenix (Rel. 1.35) by Joe DiAdamo. It is reported that it fails on partitions greater than 2Gb or with HPFS 2.3 (not verified).

Parameters
Default is D, This value is expressed in Kbytes.
 * /AUTOCHECK:value
 * Will make CHKDSK process locked drives. Ex: /AUTOCHECK:*
 * /C:value or /CACHE:value
 * Determines the cache size. Value can be D or in the range from 1 to 2048. If set to D the cache size is 10% of RAM up to the maximum of 2048 Kbytes.
 * /CRECL:value
 * Specifies the maximum file size to be cached. If a file is greater than this value the file is not cached. Value can be in the range from 2 to 64 in multiplies of 2. Default = 4 This value is expressed in Kbytes.
 * /AC:drives
 * The AC parameter specifies which drives should be checked by chkdsk.exe during start up after an improper shut down. Add only the drive letter without the colon. If you want to run chkdsk.exe on a drive at every start up add a plus sign (+) in front of the drive letter.
 * /F:level
 * Indicates on which level chkdsk.exe should be run. Level can be in the range from 1 to 3. Default is 2
 * /Quiet
 * If this option is set up, the Hpfs.ifs driver will show no error messages at boot up. This parameter can not be the last parameter!
 * /Force
 * With this option set you can get access to a disk that is marked as bad and is not in the Autocheck list (the /AC: parameter). But beware there are may errors in the file system, so run chkdsk as soon as possible.
 * The following line sets up a two megabyte cache size, allows only files which are not greater than 32 Kbytes to be cached and autochecks drive C: and drive D: after an improper shut down: IFS=C:\OS2\HPFS.IFS /CACHE:2048 /CRECL:32 /AC:CD