File Name Mapping

On Solaris system files and directories, you can have names of up to 255 characters, far greater than the MS-DOS operating system 8.3 standard. And, while Windows NT Workstation and Windows NT Server users will see the long Solaris file name in a SunLink Server directory, users of client computers running Windows for Workgroups--which uses the MS-DOS 8.3 name convention--would not. To ensure access to all Solaris files by all users, the SunLink Server program provides name mapping: each file or directory with a name that does not conform to the MS-DOS 8.3 standard automatically is given a second name that does conform.

Many Microsoft Windows 3.1 and Windows for Workgroups users connecting to the file or directory over the network see the name in the 8.3 format; Windows NT Workstation and Windows NT Server users see the long name. (Note, however, that the SunLink Server program does not generate short names for share names that do not conform to MS-DOS naming standards, but only for files and directories with long names. When naming a share, use the 8.3 standard to avoid potential file name conflicts.)

SunLink Server name mapping also allows applications that do not support long file names to access files with such names. These applications refer to files that have long names by their shorter names.

If an application that does not support long file names opens a file with a long name and then saves the file, the long name is lost and only the short name remains.

SunLink Server file name mapping is composed of the following three elements:

• Mixed-case support

• Mapping Solaris system file names to the 8.3 convention

• Mapping Solaris system file names containing characters that are unacceptable in Windows NT to names that are acceptable to Windows NT

The challenge of mapping between name spaces is resolved on Solaris systems by concatenating a truncated file name with a pseudo-unique suffix, which is generated dynamically from the i-node number of the Solaris system file.

File Name Mapping Rules

For mapping Solaris system file names to 8.3-type file names, the following default rules apply:

• Spaces are removed from the name.

• Periods are removed, except for the last one followed by at least one character.

• Invalid characters are replaced by underscores (_).

• The name, not including suffix, is truncated; a tilde (~) separator and a combination of numbers (0 - 9) and letters (A - Z) are appended.

• The suffix (the characters following the tilde separator) is truncated to three characters.

For example, the file name longfilename.txt and i-node number of 11455, would have a mapped name of long~8u7.txt.

For mapping from Solaris system file names to Windows NT-style file names, the following default rules apply:

• Invalid characters are replaced by underscores (_).

• A mapping separator (a tilde by default) and a combination of numbers (0 - 9) and letters (A - Z) are appended to the name, not including the extension.

• The extension is preserved.

For example, the file name k<l<m.expression and i-node number of 8461 would have a mapped name of k_l_m~6j1.expression.

Considerations for Using Mixed-Case Support

A decision on whether your server should continue to support mixed-case file names--which is the default in the SunLink Server program--should be considered carefully. Mixed-case support allows clients to have access to file names on Solaris systems that contain uppercase characters, but turning off this feature could improve server performance.

It is inadvisable to switch frequently between mixed-case support on the same server. While mixed-case support is enabled, clients can create files with mixed-case names. These files will become unavailable to them as soon as mixed-case support is disabled. If mixed-case support is changed from enabled to not enabled, every existing file name should be made lowercase.

Do not create file names that are case-insensitively identical in the same directory. Although the Solaris system is case-sensitive, SunLink Server mixed-case support causes the server to preserve case but behave in a case-insensitive way, just like Windows NT. Microsoft product users are not aware of the possibility of having case-insensitive similar file names in a directory, because Windows NT does not allow such files. As a result, users may become confused if they access incorrect files or are denied access to files they need.