OS/2 File Systems Comparison

This table is from the WSeB "Quick Beginnings" book.

Flle System Comparison: JFS, 386 HPFS, HPFS, and FAT

Characteristic
Journaled File System
(JFS)
386 High Performance File
System (386 HPFS)
High Performance File
System (HPFS)
FAT File System
Maximum volume size
2TB (terabytes)
64GB (gigabytes)
64GB (gigabytes)
2GB (gigabytes)
Maximum file size
2TB (terabytes)
2GB (gigabytes)
2GB (gigabytes)
2GB (gigabytes)
Maximum file name length
254 characters (bytes)
254 characters (bytes)
254 characters (bytes)
11 (8.3 format) characters
Allows spaces and periods in file names
Yes
Yes
Yes
No; however, a period is required between file name and extension
Standard file and directory attributes (bit flags)
Within file system
Within file system
Within file system
Within file system
Extended attributes (64KB text or binary with keywords)
Within file system
Within file system
Within file system
In a separate file
Maximum path length
260 characters (bytes)
260 characters (bytes)
260 characters (bytes)
64 characters (bytes)
Bootable file system
No
Yes
Yes
Yes
Logical volume type
LVM only
LVM or compatibility (must be compatibility for Fault Tolerance)
LVM or compatibility
LVM or compatibility
Allows dynamic volume expansion
Yes
No
No
No
File system scales up when using SMP
Yes
No
No
No
Allows for fault tolerance
No
Yes
No
No
Allows for local security
No
Yes
No
No
Requires a separate proof of license during installation
No
Yes
No
No
Average wasted space per file
1/2 block size (256 to 2048 bytes)
1/2 sector (256 bytes)
1/2 sector (256 bytes)
1/2 cluster (1 KB to 16KB), approximately 0.001% of volume
Allocation information for files
Near each file in its INODE
Near each file in its FNODE
Near each file in its FNODE
Centralized near front of volume
Free disk-space information
Centralized in file structure represented by B+tree
Located near free space in bit maps
Located near free space in bit maps
Centralized near front of volume
Directory structure
Sorted B+tree
Sorted B-tree
Sorted B-tree
Unsorted linear list; must be searched exhaustively
Directory location
Close to files it contains
Located near seek center of volume
Located near seek center of volume
Root directory at front of volume; others scattered
Read-ahead
32MB
Sensitive to data type
Cache reads in 8KB blocks
Optional
Cache replacement strategy
Segmented least recently used (LRU) algorithm
Sensitive to data type
Modified least recently used (LRU) algorithm
Simple least recently used (LRU) algorithm
Write-behind (lazy write)
Optional; can be handled on a per-file basis
Optional; can be handled on a per-file basis
Optional; can be handled on a per-file basis
Optional; can be handled on a per-file basis
Caching program
None; lazy write parameters can be set on the IFS=JFS.IFS line in the CONFIG.SYS file)
CACHE386-EXE (values specified for the IFS and RUN statements in the CONFIG.SYS file) and HPFS386.INI
CACHE.EXE (in the CONFIG.SYS file)
DISKCACHE (in the CONFIG.SYS file)
Maximum cache size
Physical memory available
Physical memory available
2MB
14MB
Cache threshold
No cache threshold
Sensitive to data type
Variable, up to 64KB
Variable, up to 64KB; 3.5KB default
LAN Server access control lists
Within file system
Within file system
In separate file (NETACC)
In separate file (NETACC)
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