The following special features must be borne in mind when processing bs2fs files systems which are mounted on NFS clients:
When files or library members are created, copied or renamed, the relevant naming regulations of BS2000 must be observed, otherwise the error number EINVAL ("invalid argument") will be returned to the application when open() takes place. This can, for instance, lead to problems in the case of:
editors which automatically generate copies of the original file or save intermediate results (.filename.swp, filename~, etc.)
file browsers which generate thumbnails of files and store these temporarily in the relevant directory
As a rule this can be configured in the editors or browsers either by disabling the function concerned or by selecting a storage location outside the bs2fs file system.
In order to optimize internal performance, the closing of a bs2fs file on the NFS server is slightly delayed (by 2 seconds) if there is no shortage of space in the bs2fs container. As a result, a file on the NFS server remains open for 2 seconds and from the viewpoint of BS2000 remains locked for this time although, from the viewpoint of the NFS client, it already appears to have been closed.
The first open() of the bs2fs file as a rule takes place when the client application calls the access() function. This can result in the response time of the NFS function ACCESS being unexpectedly long. The response time in particular also depends on the size of the bs2fs file (see also "Recommendations for mounting bs2fs file systems on NFS clients").
On UNIX file systems, the hard link count of directories is the same as the number of subdirectories plus two (because of the pseudo directories "." and ".."). In bs2fs file systems the mountpoint and also PLAM libraries can contain subdirectories. For them, the hard link count is set to this value only when the directory contents are read (readdir function; used, for example, by the ls command). Before this the count is 2 or the value which the last call of the readdir function supplied.
In some UNIX applications this leads to problems. The find command on LINUX clients (GNU variant) can, for example, under some circumstances issue a warning that the hard link count of a directory is incorrect and therefore internal optimization algorithms do not function correctly and suggests that this optimization should be disabled.The file type detection on UNIX systems as a rule takes place by means of a heuristic examination of a small part of the file contents. For this purpose the file is opened, a specific quantity of data is read and analyzed, and the file is closed again. In the case of bs2fs files the entire BS2000 file must first be copied into the bs2fs container on the NFS server to permit this, and the larger the file is the longer this process takes.
This can result in very long wait times on the NFS client which depend on the total size of the files in this directory.