JFS and JFS2 functions
Enhanced Journaled File System (JFS2) is a file system that provides the capability to store much larger files than the existing Journaled File System (JFS).
You can choose to implement either JFS or JFS2. JFS2 is the default file system in AIX 6.1.
Note: Unlike the JFS file system, the
JFS2 file system will not allow the link() API to be used on files of type directory. This
limitation may cause some applications that operate correctly on a JFS file system to fail on a JFS2
file system.
The following table provides a summary of JFS and JFS2 functions:
| Functions | JFS2 | JFS |
|---|---|---|
| Fragments and block size |
Block sizes (bytes): 512, 1024, 2048, 4096 Maximum size of the file system with block size of 4096 bytes, when the value of the lff attribute is set to yes, in petabytes (PB): 4 Maximum size of the file system when the value of the lff attribute is set to no, in terabytes (TB): 4, 8, 16, 32 Note: The lff attribute is only supported on a file system with an aggregate
block size of 4096 bytes.
|
Fragment sizes (bytes): 512, 1024, 2048, 4096 Maximum size of the file system in gigabytes (GB): 128, 256, 512, 1024 |
| Maximum file system size | 4 PB | 1 TB |
| Minimum file system size | 16 MB | Not Applicable |
| Maximum file size | 4 PB | Approximately 63.876 GBs |
| Number of i-nodes | Dynamic, limited by disk space | Fixed, set at file system creation |
| Directory organization | B-tree | Linear |
| Compression | No | Yes |
| Quotas | Yes | Yes |
| Error logging | Yes | Yes |
Note:
- JFS2 supports the standard AIX error logging scheme. For more information on AIX error logging, please see Error-Logging Overview in General Programming Concepts: Writing and Debugging Programs.
- The maximum size values of the JFS2 files and filesystems that are mentioned in the Table 1 table are theoretical limits. For currently certified values of the maximum size of JFS2 file and fiesystems when you use the lff=yes option, refer to the AIX Release Notes.