Security

Fileshare on UNIX

Chapter 6: Advanced Operation

This chapter describes the advanced features that are available with Fileshare.

Note: In Mainframe Express, Fileshare is only supported for use by the components of Mainframe Express. Therefore some of the following information about writing applications that use Fileshare is not relevant to Mainframe Express users.

6.1 Single User Mode

You can configure Fileshare to run in single user mode. All network communication is bypassed and the Fileshare Client makes direct calls to the Fileshare Server module. The Fileshare Server does not run as a separate process in this mode of operation.

This is useful when:

You want to develop Fileshare applications without using a network or multiple sessions
A single-user application makes use of one of Fileshare's advanced features, such as transaction processing

To run Fileshare in single user mode, set the FSCOMMS environment variable to $local, for example:

Windows:
set FSCOMMS=$local

UNIX:
set FSCOMMS="\$local" export FSCOMMS

Even when you are running in single user mode, you must still inform the Fileshare Client which Fileshare Server to use, either by specifying the Fileshare Server name as part of the filename in your program or by using a Fileshare Client configuration file.

The Fileshare Server is configured in the normal way using a Fileshare Server configuration file. At the minimum, you must define a Fileshare Server name in this file.

Note: The Fileshare Server does not have control over the screen when it is running in single user mode. It directs all screen output to the file fsscreen.lst in the current Fileshare Client directory. If your program fails, check this file for messages.

6.2 Filename Mapping

Filename mapping enables I/O requests made against one data file to be mapped to a different data file when your program is executed. For example, you can use filename mapping to enable applications that use DOS file naming conventions to access data files under the control of a Fileshare Server running on an operating system that uses different file naming conventions, such as UNIX or NetWare.

You do not need to change the configuration of the Fileshare Client to use filename mapping.

6.2.1 Fileshare Server

To enable filename mapping, use the /af (alternate filename) option with the /f option in the database reference file.

The /fs (filename string) option used in conjunction with the /af option enables you to substitute characters at the start of a filename. This is particularly useful for mapping pathnames.

For example:

fs /d dbase.ref /f old.dat /af new.dat
fs /d dbase.ref /fs c: /af e:

adds entries to the database reference file dbase.ref which specify that:

All requests to the data file old.dat are redirected to the data file new.dat
All accesses to data files starting with c: are directed to drive e:

If the Fileshare Server finds an entry specifying an alternate filename, any character string substitution specified by a /fs option is applied to the new filename.

After processing any string substitution specified by an /fs option, the Fileshare Server does not search the database reference file for any matching /f option using the new filename.

Fileshare processes all filenames as relative to the Fileshare Server's current directory if you have not given a fully qualified filename after the /f option or a fully qualified filename is not passed from the Fileshare Client.

All filenames and paths are forced to upper case by Fileshare Servers not running on the UNIX operating system and are expanded to include the full path to ensure matching. Filenames specified with the /af option are not modified.

Example 1:

fs /d dbase.ref /f file1.dat /af c:\data\file2.dat

This example adds entries to the database reference file dbase.ref that specify that file accesses to the file file1.dat are mapped to the alternate filename file2.dat.

Example 2:

fs /d dbase.ref /f file1.dat /af c:\data\file2.dat
fs /d dbase.ref /fs c: /af e:

This example adds entries to the database reference file dbase.ref that specify that all requests made to the data file file1.dat are redirected to the alternate filename and, in addition, the alternate filename is changed, using string substitution, to be on drive e:.

6.3 Data and Key Compression

You can configure the Fileshare Server so that data files are created using data or key compression.

You do not need to change the Fileshare Client configuration in order to use data or key compression on a data file.

6.3.1 Data and Key Compression - Fileshare Server

To enable data or key compression for a data file, use the /k option in the database reference file. In conjunction with the /k option, use the d option to specify data compression and the i option to specify key compression.

Values that you specify after the d and i options are the same values that you would specify using the Compiler directives DATACOMPRESS and KEYCOMPRESS.

Data and key compression specifications in the database reference file are effective only if the Fileshare Server creates the data files. They do not affect existing data files. For existing files, the data and key compression information is retrieved from the data file header. Any settings in your program or the database reference file are ignored.

Example

fs /d dbase.ref /f file1.dat /k d001
fs /d dbase.ref /f file2.dat /k d001i7

This example tells the Fileshare Server to create the file file1.dat with data compression and the file file2.dat with both data and key compression.

6.4 Virtual File Handler Interface

The Fileshare Server can pass I/O requests to a program specified by you, rather than by the Micro Focus File Handler, as long as the program that you specify conforms to the call interface used by the File Handler.

You do not need to change the configuration of the Fileshare Client to use the Virtual File Handler Interface.

6.4.1 Fileshare Server

To specify a virtual file handler, use the /ap (application program) option with the /f option in the database reference file to specify the program to which I/O requests for a particular data file are passed by the Fileshare Server.

Example:

fs /d dbase.ref /f user1.dat /ap myprog

This adds entries to the database reference file, dbase.ref which specify that the Fileshare Server should pass all I/O requests for the data file user1.dat to the program myprog.

Windows:
Your program should be in .obj file format and needs to be linked into the main Fileshare module, FS.DLL. See the section Linking the Fileshare Server on Windows for further details.

UNIX:
Your program should be compiled to intermediate or generated code, or to a callable shared object, and must be callable from the Fileshare process.

6.5 Monitoring Fileshare

When the Fileshare Server is active, you can toggle the trace option on and off using the F2 key. If the trace option is on, the Fileshare Server displays the file access requests on the console as they happen. Each line of trace provides:

Input:
- The user-ID assigned, in the order that the Fileshare Clients logged onto the Fileshare Server
- The operation code, indicating the I/O operation requested (see the Net Express online help on the Micro Focus File Handler for further information about operation codes)
- The name of the file being accessed
Output:
- The status returned to the Fileshare Client, indicating the result of the operation

Note: The trace option can degrade performance. You should only use it as a diagnostic aid in problem investigation.

You can activate the trace option when the Fileshare Server is started using the /tr f option. This causes the trace to be written to the file fsscreen.lst, as well as being displayed on the screen. Note, however, that this severely impacts the Fileshare Server performance if tracing is switched on. If, however, tracing is switched off, only information messages are written to the screen and to the file. This is a useful method of keeping a permanent record of Fileshare messages on disk.

If you are using Fileshare in single user mode (see the section Single User Mode), the trace display, together with all other output normally displayed on the Fileshare Server console screen, is written to the file fsscreen.lst in the Fileshare Server's current directory .

6.6 Fileshare Manager

You can use the Fileshare Manager (fsmgr) to automate some of Fileshare's supervisor mode functions by writing a COBOL program to call it. The Fileshare Manager can be called to instruct a Fileshare server to:

Perform an automatic backup of its recovery log file
Close all of its currently open data files. Any client application accessing these files is returned a file status, indicating that the file is no longer open. This is particularly useful in the event of a system crash or power failure, either of which could cause a Fileshare client program to terminate without disconnecting properly from Fileshare. If this happens, and data files are left open on the Fileshare server, it can prevent automatic disk backups from running and possibly prevent other clients from accessing the files.
Log off any clients currently connected to it, close any open files and roll back any incomplete transactions belonging to these clients.Any subsequent access attempts by these client applications result in an error status (9/125).
Close down completely. Any open files are closed and any incomplete transactions rolled back
Close down completely and then re-start. If a backup directory has been specified in the database reference file, Fileshare copies all the files named in the database reference file to the backup directory, deletes the recovery log file(s) and re-starts with a new recovery log file.

Note: Any Fileshare Clients connected to the Fileshare Server when this instruction is issued will be logged off and any files which they had open will be closed.

6.6.1 Call Interface

The Fileshare Manager program (fsmgr) is called from a COBOL program as follows:

call "fsmgr" using parameter-block

Parameters:

parameter-block        A group item defined as:
   function-code         pic xx comp-x.
   error-status          pic xx comp-x.
   fileshare-name        pic x(16).
   supervisor-passwd     pic x(20).
   reserved              pic x(24).

On entry:

`function-code`	The Fileshare Manager program function required: 1 = Backup recovery log file 2 = Close all open data files 3 = Log off all connected clients 4 = Shut down Fileshare 5 = Shut down and re-start Fileshare
`fileshare-name`	The name of the Fileshare server (this is the name that was used when Fileshare was started)
`supervisor-passwd`	The supervisor password. See the section Supervisor Mode in the chapter Security for more information
`reserved`	Reserved for future use. Must contain binary zeros.

On exit:

error-status Reflects the success, or failure, of the call. Possible values of error-status are shown below.

Value	Meaning
0	Function completed successfully
1	Communications error. A Fileshare server of the name specified in fileshare-name could not be contacted on the network using the specified communications protocol. This error is also returned if a network failure occurs during the execution of the function but after the initial connection was made. Check that fileshare-name is specified correctly and that the Fileshare Handling Redirection module (FHRedir) is configured to use the correct communications protocol.
2	File error during initial connection. To connect to Fileshare, the Fileshare Manager opens a file called fsmgr.ctl. This file should not already exist and the Fileshare Manager does not actually create it. If it does exist, this status is returned if there is a subsequent error in closing the file.
3	Invalid password specified in supervisor-password. Ensure that Fileshare is running with a password file and that the contents of supervisor-password match the supervisor password entry in the password file. Note that Fileshare passwords are case sensitive. See Supervisor Mode in the chapter Security for more information.
4	Invalid value specified in function-code - must be within the range one to five
5	No Fileshare log file. You have attempted to backup the log file on a Fileshare server that is running without a recovery log file.
6	Function 2 or 3 could not complete. While attempting to log off all Fileshare's clients (function 3), it is possible for other clients to log on before the logging off operation completes. For example, the Fileshare Manager has to send a `logoff client n` request four times if there are four clients logged on. If, however, a new client logs on before all four original clients have been logged off, the Fileshare Manager retries the `logoff client n` request in order to log off the new client. It retries 10 times and if new clients are still logging on, it returns error 6. A similar situation can occur during processing of a function 2 (close all data files) if new files are continuously being opened at the same time.
10	Other error

6.6.2 Fileshare Manager Configuration

Fileshare Manager, like other Fileshare Client applications, accesses a Fileshare server via the Fileshare Handling Redirection module (FHRedir) and so needs to be configured to use the correct communications protocol. See the section Client Configuration in the chapter Configuration for more information.

6.6.3 Linking Fileshare Manager Applications

If your program calls the Fileshare Manager, you need to link in the Fileshare manager object file (fsmgr.obj on Windows, fsmgr.o on UNIX) when you create an executable file.

6.7 Byte-stream I/O Calls

Fileshare supports some of the byte-stream I/O routines that are available with this COBOL system. Most of the routines use the same parameters and have the same effect as the corresponding COBOL system call, but access remote files via Fileshare. The only change needed to your program is to call the routine starting with FS_ instead of CBL_. The only routine that does not have exactly the same call interface as its corresponding CBL_ routine is FS_LOCATE_FILE.

Fileshare supports the following byte-stream I/O routines:

FS_CHECK_FILE_EXIST
FS_CLOSE_FILE
FS_CREATE_FILE
FS_COPY_FILE
FS_DELETE_FILE
FS_JOIN_FILENAME (see below)
FS_LOCATE_FILE (see below)
FS_OPEN_FILE
FS_READ_FILE
FS_RENAME_FILE
FS_SPLIT_FILENAME (see below)
FS_WRITE_FILE

You can use these routines to access files on remote Fileshare servers, as well as local files. Configure the Fileshare Client in the normal manner to define which files are local and which are remote.

Notes:

Do not use byte-stream I/O and COBOL I/O on the same file
If you want to share files between multiple Fileshare Clients you must access the files using normal COBOL I/O verbs

6.7.1 FS_LOCATE_FILE

The functionality provided by FS_LOCATE_FILE is the same as CBL_LOCATE_FILE except:

You cannot use FS_LOCATE_FILE to search for files in libraries on remote Fileshare Servers
You can use CBL_LOCATE_FILE to search for files along each path specified in an environment variable. You can then use the returned actual-file-spec as the filename when opening the file.
If you have specified a $$server-name prefix in user-file-spec, actual-file-spec must contain the same $$server-name prefix for an OPEN using actual-file-spec to be re-directed automatically. By default, Fileshare only returns the filename in actual-file-spec to your program. To return the $$server-name in actual-file-spec, set the most significant bit of user-mode before making the call to FS_LOCATE_FILE.
When a remote file is found, using an environment variable containing many paths, FS_LOCATE_FILE returns actual-file-spec including the full path where the file is located

6.7.2 FS_SPLIT_FILENAME and FS_JOIN_FILENAME

The functionality provided by FS_SPLIT_FILENAME and FS_JOIN_FILENAME is the same as that provided by the corresponding CBL_routines. In addition, using FS_SPLIT_FILENAME and FS_JOIN_FILENAME you can process filenames that specify Fileshare Server names using the $$server-name prefix at the front of the filename. When processing such filenames, the $$server-name prefix characters are included as part of the pathname parameter.

6.8 Running Fileshare as a Windows NT Service

Windows NT:
You can install the Fileshare Server so that it runs as a Windows NT service by entering the following at the command prompt for this MERANT product:

fsservice -i

Once installed, you can display the status of the service by entering:

fsservice -v

and you can uninstall Fileshare as an NT service by entering:

fsservice -u

Once Fileshare is installed as an NT service, you can start it as a background process as follows:

Select the Services icon from the Control Panel
Select Micro Focus Fileshare Service from the list of displayed services
Click Start

You can stop the Fileshare service as follows:

Select the Services icon from the Control Panel
Select Micro Focus Fileshare Service from the list of displayed services
Click Stop

Notes:

When you select Stop from the NT Services window, Fileshare closes down as normal. Any connected Fileshare clients are logged off and their data files closed (with any incomplete transactions rolled back).
Shutting down Windows NT similarly closes down Fileshare

You can specify that the Fileshare Server should be started up automatically when Windows NT boots up as follows:

Select the Services icon from the Control Panel
Double-click on Micro Focus Fileshare Service
Select Automatic as the Startup Type

Note: If you have specified that the Fileshare Service is to be started automatically when Windows NT boots up and you have logging switched on for any data files, we recommend that you specify a Fileshare backup directory in your database reference file. See the section Automatic Database Backup and Rollforward Recovery in the chapter Database Integrity for more information.

Before starting Fileshare, you need to create a Fileshare Server configuration file so that you can specify Fileshare Server options. For more details on Fileshare Server options, see the section Server Configuration in the chapter Configuration.

The Fileshare Service inherits the Windows system directory (for example, c:\winnt\system32) as its current directory and so you should place your Fileshare Server configuration file in this directory. If you want Fileshare to use a different working directory, you can specify this using the /wd option as the first entry in your configuration file. On start-up, Fileshare changes to your specified working directory and accesses any files that are not fully qualified as being relative to this working directory, for example, a database reference file.

Because Fileshare runs as a background process, any messages it generates are written to the file fsscreen.lst in the current working directory. Check the contents of this file to diagnose any problems.

Example Configuration File

The following is an example of a Fileshare Server configuration file:

/wd d:\fsdir
/s server1
/d dbase.ref

where the first line specifies the directory fsdir on the drive d: as the Fileshare Server's current directory. Any data files without fully qualified pathnames are searched for, relative to this directory. The second line specifies that the Fileshare Server is to register its name on the network as server1 and the third line specifies that Fileshare is to use the database reference file dbase.ref. Because this name is not fully qualified it is searched for in Fileshare's current directory, that is, d:\fsdir.

6.9 Linking the Fileshare Server on Windows

Windows:
If you want to use the Virtual File Handler Interface or your own security modules on Windows, you need to recreate the file fs.dll. You can do this by entering a command line similar to the following:

CBLLINK -ofs.dll -d -RE,2.0 -Mfscmd fscmd.obj fsserver.obj
   fhxscomp.obj fsseclog.obj fsinstpw.obj fsinst.obj fsrcvr.obj
   fspthnam.obj fssecopn.obj fsossec.obj cbldc001.obj _codeset.obj
   mfini.obj

Alter this command line to suit your own purposes by adding object modules or substituting security modules as necessary.

Alternatively, if you are running Fileshare as a Windows NT Service, you will need to relink the fsservice.exe module using a command similar to the following:

cbllink -ofsservice.exe -Rm,+2.0 fssrvice.obj  CblNTService_Handler.obj
   CblNTService_SetStatus.obj CblNTService_ServiceRoutine.obj 
   servserv.obj fscmd.obj fsserver.obj fhxscomp.obj fsseclog.obj 
   fsinstpw.obj fsinst.obj fsrcvr.obj fspthnam.obj fssecopn.obj
   fsossec.obj cbldc001.obj _codeset.obj mfini.obj

Then uninstall the old version of fsservice and install this new version.

6.10 Performance Considerations

Although Fileshare reduces the number of requests made across the network for COBOL I/O, some types of data file access benefit more than others. The following areas affect Fileshare's ability to improve the speed of accessing remote data:

File organization
A single request to an indexed data file can involve many accesses to the physical data file itself such as reading the header and updating the integrity marker. Complex key structures also increase the number of accesses needed to update the index structure in the file. Using the normal COBOL file handling system, each of these accesses generates a request that is sent across the network. Using Fileshare, only one request is sent across the network. The simpler data file organizations (relative and sequential files) involve a smaller processing overhead.

Any speed improvements using Fileshare are therefore more apparent when processing indexed data files.
I/O request
The number of accesses to a data file needed to process a WRITE, DELETE or REWRITE operation is generally larger than the number needed to process a READ or START operation. Using the normal COBOL file handling system, each of these accesses generates a request that is sent across the network. Using Fileshare, only one request is sent across the network.

Any speed improvements using Fileshare are therefore more apparent when performing WRITE, DELETE or REWRITE operations.
Concurrent use of data files
If your program opens a data file exclusively, the normal COBOL file handling system uses caching. This means that it does not have to check to see if the file has been updated on every I/O operation. The number of requests sent across the network, therefore, is significantly less if the data file is opened exclusively.

Fileshare provides a greater improvement in performance, therefore, when a large number of users require concurrent access to data files than when files are opened exclusively. This is because access and caching are controlled by the Fileshare Server and so the additional requests needed when accessing a shared data file via the normal COBOL file handling system are not needed.

Any speed improvements are therefore very specific to individual applications and become more pronounced as more Fileshare Clients concurrently access the same data files.

UNIX:
On UNIX, when running the Fileshare Server and Fileshare Client on the same machine, we recommend that you use the CCINAMPU CCI protocol as it performs better in this situation than the CCITCP protocol.

6.10.1 Fileshare Performance on UNIX

Fileshare improves performance when remote COBOL applications are concurrently accessing shared data files across a network but it cannot improve peformance when the COBOL data resides on the same machine as the application. In this configuration, there is actually a performance overhead when using Fileshare instead of the standard Callable File Handler.

Although UNIX machines can be used as remote data servers, it is not uncommon for the application itself to run on the machine where the data resides. For example, multiple users may log in, across a network, to a machine where they run applications which share the same data. In such a configuration, you encounter the performance overhead of using Fileshare, making performance slower than when using the standard Callable File Handler.

6.11 Large File Support with Fileshare

Fileshare, by default, supports files that can be up to 4 Gigbytes in size. If your operating system supports larger files, you can configure the file handler used by Fileshare to allow sequential, relative and IDXFORMAT(8) indexed files greater than the default 4 Gigabytes.

An alternative technology, file striping, was introduced in previous releases as an interim solution to overcome limitations on the maximum allowed file size. It enables you to specify that a single data file is to be stored in multiple physical files (or stripes) on disk.

Because of the complications involved with configuring striping together with Fileshare (these issues are discussed below), we recommend that you keep your large files non-striped and instead, configure the file handler to use its standard large file support.

If you are using Net Express, you should also review the chapter File Handler Configuration in your File Handling book.

To configure large file support under Fileshare, you should consider the following:

Location of the extfh.cfg file
The extfh.cfg file must be located in the same directory as the Fileshare Server or, if the EXTFH environment variable has been set to point to the extfh.cfg file, it must have been set in the Fileshare Server session.
Switching on large file support
Add the following line to the extfh.cfg file:

[XFH-DEFAULT] Filemaxsize=8

The following information explains how to configure striped files under Fileshare control if your operating system does not support large files:

Expanded filenames in the extfh.cfg file
You must use the fully qualified name of the base file in the extfh.cfg configuration file. This name includes the pathnames that you can see if you press F2 at the Fileshare Server to switch tracing on.

Example:

UNIX:
[/u/username/file.dat] Striping=on

Note: You need only do this for files accessed through Fileshare. To enable the file handler to find the setting in extfh.cfg the filename tag must match exactly that specified by the I/O request, which in the case of Fileshare includes a fully qualified path.
Backslash character
The backslash character is treated as an escape character within the extfh.cfg file. On Windows platforms you must therefore specify two backslash characters for each backslash character in the pathname, for example:

Windows:
[d:\\fsrvr\\file.dat] Striping=on
Alternate filenames
You can specify file striping on an alternate filename (specified in the database reference file using filename mapping). In this case, the expanded filename is not required. For example, if the database reference file contains the following line:
```
/f file1.dat /af file2.dat
```
you can specify the following in the extfh.cfg file:

[file2.dat] Striping=on
StripeNameType
StripeNameType=1 (the default is StripeNameType=0) only works with Fileshare if the base filename does not have an extension. If you specify StripeNameType=1 for a filename that has an extension, the file is created but it is not striped.
Back up and recovery
The use of striping complicates the process of logging for rollforward recovery because the administrator has to ensure that the correct versions of the files are in the latest backup, and that they are correctly restored in the event of needing to run the Fileshare Recovery Utility. This process is much more complex if file stripes also have to be maintained.

The Automatic Database Backup and Recovery facility does not work correctly on striped files because it uses low-level I/O routines for backups and restores which are unaware of the stripe configuration.
Not using Fileshare
The filenames passed to the File Handler must match exactly so that the File Handler can locate the filename tags in the extfh.cfg file.

Generally, only Fileshare passes fully qualified names. Therefore, if you have set up an extfh.cfg file for use under Fileshare with expanded pathnames and then want to access the files outside of Fileshare, you need to change the filename tags in extfh.cfg to match exactly the filenames passed by the application.

Security

Fileshare on UNIX