*TYPE2 directories

The "root" (/), QOpenSys, and user-defined file systems (UDFS) in the integrated file system support the *TYPE2 directory format. The *TYPE2 directory format is an enhancement of the original *TYPE1 directory format.

Note: The concept of *TYPE1 and *TYPE2 stream files is different from the concept of *TYPE1 and *TYPE2 directory formats. One does not relate to the other.

*TYPE2 directories have a different internal structure and different implementation than *TYPE1 directories.

The advantages of *TYPE2 directories are:

Improved performance
Improved reliability
Added functionality
In many cases, less auxiliary storage space

*TYPE2 directories improve file system performance over *TYPE1 directories, especially when creating and deleting directories.

*TYPE2 directories are more reliable than *TYPE1 directories. After a system abnormally ends, *TYPE2 directories are completely recovered unless there has been an auxiliary storage failure. *TYPE1 directories may require the use of the Reclaim Storage (RCLSTG) command in order to recover completely.

*TYPE2 directories provide the following added functionality:

*TYPE2 directories support renaming the case of a name in a monocase file system (for example, renaming from A to a).
An object in a *TYPE2 directory can have up to one million links compared to 32 767 links for *TYPE1 directories. This means you can have up to 1 million hard links to a stream file, and a *TYPE2 directory can contain up to 999 998 subdirectories.
Using System i® Navigator, the list of entries are automatically sorted in binary order when you open a directory that has the *TYPE2 format.
Some new functions such as integrated file system scanning support are only available for objects in *TYPE2 directories.

Typically, *TYPE2 directories that have fewer than 350 objects require less auxiliary storage than *TYPE1 directories with the same number of objects. *TYPE2 directories with more than 350 objects are ten percent larger (on average) than *TYPE1 directories.

There are several ways to get *TYPE2 directories on your system:

New System i platforms that are preinstalled with OS/400® V5R2 or IBM® i V5R3, or later, have *TYPE2 directories. No conversion is needed for "root" (/), QOpenSys, and UDFSs in ASPs 1-32.
If you install OS/400 V5R2 or IBM i V5R3, or later, on a System i platform for the first time, the platform has *TYPE2 directories. No conversion is needed for "root" (/), QOpenSys, and UDFSs in ASPs 1-32.
The V5R2 conversion utility is used to convert the file systems. For more information about the conversion utility, see the Convert to a *TYPE2 directory section in the V5R2 iSeries Information Center.
If the UDFSs in an independent ASP have not yet been converted to the *TYPE2 format, they will be converted the first time that the independent ASP is varied on to a system installed with OS/400 V5R2 or IBM i V5R3 or later.
All other supported file systems except UDFSs on independent ASPs that are still using *TYPE1 directories are converted automatically by the system. This conversion begins after the installation of IBM i V5R3 or later releases. It should not significantly impact your system activity.

To determine the directory format for the file systems on your system, use the Convert Directory (CVTDIR) command:

CVTDIR OPTION(*CHECK)

Note: *TYPE2 directories are supported on OS/400 V5R2 or IBM i V5R3 or later, but there are some differences from normal *TYPE2 directory support.