There are many differences between JFS and Enhanced JFS.
|Optimization||32-bit kernel||64-bit kernel|
|Maximum file system size||32 terabyte||4 petabytes
Note: This is an architectural limit. AIX® currently only supports up to 16 terabytes.
|Maximum file size||64 gigabytes||4 petabytes
Note: This is an architectural limit. AIX currently only supports up to 16 terabytes.
|Number of I-nodes||Fixed at file system creation||Dynamic, limited by disk space|
|Large file support||As mount option||Default|
|Direct I/O support||Yes||Yes|
- Cloning with a system backup with mksysb from a 64-bit enabled JFS2 system to a 32-bit system will not be successful.
- Unlike the JFS file system, the JFS2 file system will not allow the link() API to be used on its binary type directory. This limitation may cause some applications that operate correctly on a JFS file system to fail on a JFS2 file system.
Before writing actual data, a journaling file system logs the metadata, thus incurring an overhead penalty that slows write throughput.
- Directory organization
An index node, or i-node, is a data structure that stores all file and directory properties. When a program looks up a file, it searches for the appropriate i-node by looking up a file name in a directory.
The main advantage of using Enhanced JFS over JFS is scaling.