OS/2 2.0 comes with a choice of two file systems, HPFS and FAT.
The HPFS under OS/2 2.0 supports the following:
- Command chaining by calling the volume manager with a list of all
contiguous sector requests required to fulfill an I/O request.
This function is supported for all DASD types.
- Scatter and gather by passing physical pointers to each page in
the data buffer (physically discontiguous) as part of the I/O
request. This enables I/O controllers, such as the IBM SCSI
adapters, that support the scatter and gather capability to
perform the I/O in a single operation.
- Disk caching in the IFS driver, rather than in the device driver.
- Recognition of devices that have onboard caches (nonsystem
memory), incorporating them into the total caching scheme.
HPFS under OS/2 2.0 supports a maximum file size of 2GB. The maximum
size for a disk partition is 64GB.
The FAT file system contains the following enhancements that provide
improved performance and enhanced support for disk hardware devices:
- Command chaining by attempting to call the volume manager with a
list of all contiguous sector requests required to fill an I/O
request, thereby enabling multiple page-in and page-out requests
in a single logical operation.
- Scatter and gather by passing physical pointers to each page in
the data buffer (physically discontiguous) as part of the I/O
request. This allows I/O controllers, such as the IBM SCSI
adapters, that support the scatter and gather capability to
perform the I/O in a single operation.
- Disk caching within the FAT file system, rather than in the device
driver.
- Recognition of devices that have onboard caches (nonsystem
memory), incorporating them into the total caching scheme.
- Faster allocation of free space on the logical drive, using a bit
map to track free clusters on the disk.
The FAT file system under OS/2 2.0 supports a maximum file size of
2GB. The maximum supported size for a hard disk partition also is
2GB.
Subsections