A DEVSPACE can also be created as a file of the UNIX file system. The name of such a file must already exist in the UNIX file system i order that the SERVERDB can be configured. It is recommended in this case, too, to address the file via a link in the root file system (see above), unless the SERVERDB is created in the RUNDIRECTORY (see CONTROL manual).
The easiest way to create the file is using the UNIX command "touch <filename>". This command creates a file with the name <filename> and a size of 0 bytes. Configuring the SERVERDB automatically expands the file to its correct size.
Take into account that the UNIX kernel knows maximum sizes for files. This maximum size can be requested by means of the UNIX command "ulimit". If the value defined for this parameter is too small, it has to be set to an adequate size.
Usually, the performance deteriorates when UNIX files are used as DEVSPACEs.
When the NFS lock manager is supported on both the NFS client and the NFS server, UNIX files can also be configured as DEVSPACEs via NFS. When doing so, data consistency, recovery, and performance problems may occur because NFS buffers the data, so that there is no guarantee that the data pages are immediately written to hard disk. As error correction is very difficult, if not impossible, in such a case, DEVSPACEs via NFS files must only be used for testing purposes.