==================================================================
M I C R O F O C U S C O B O L
V4.1.10
==================================================================
ENHANCED CALLABLE FILE HANDLER
==============================
TABLE OF CONTENTS
=================
INTRODUCTION
ENABLING THE ENHANCED CALLABLE FILE HANDLER
ENVIRONMENTS
NAMING CONVENTIONS
STRIPING OPTIONS
INTRODUCTION
============
By default, the Callable File Handler can handle files that are
up to a maximum of 2 Gigabytes in size. To handle larger files,
a file striping option is available which allows logical files
of up to 200 Gigabytes in size. These logical files can comprise
up to 100 physical files.
ENABLING THE ENHANCED CALLABLE FILE HANDLER
===========================================
File striping is only available if you:
- Use the IDXFORMAT Compiler directive to specify a file type
of IDXFORMAT"8".
- Build a run-time system, using the mkrts shell script, which
links in the enhanced Callable File Handler module (mFLFS).
The mFLSF module is in the directory $COBDIR/src/lfs.
Note: If you use the enhanced Callable File Handler to create
indexed files, only a single file is created (rather than
the .idx and .dat files created by the standard Callable
File Handler).
You cannot enable file striping on a global basis as this could
lead to the operating system running out of file handles so you
need to decide which files you want to use striping on.
The striping option is enabled for a particular file via the
Callable File Handler's configuration file which, by default,
is called extfh.cfg. See your "Programmer's Guide to File
Handling" for full details on the Callable File Handler
configuration file.
ENVIRONMENTS
============
The file striping option is available on 32-bit platforms, namely:
o Windows NT
o OS/2
o UNIX
Note: File striping is only available on Micro Focus file formats,
and not C-ISAM files.
NAMING CONVENTIONS
==================
With file striping, a file comprises the base file (the filename
specified by the program) and a number of stripe files.
The stripe files use the same filename as the base file, but with
a stripe number appended. For example, if the file test.dat has 3
stripes, the base file and its stripes are called:
test.dat - base file
test01.dat - stripe number 1
test02.dat - stripe number 2
test03.dat - stripe number 3
If the basename is too long to accommodate the stripe file number,
then characters are removed from the right of the basename. For
example, if the file testfile.dat has 3 stripes, the file and its
stripes are called:
testfile.dat - base file
testfi01.dat - stripe number 1
testfi02.dat - stripe number 2
testfi03.dat - stripe number 3
STRIPING OPTIONS
================
Striping options are specified in the Callable File Handler
configuration file (extfh.cfg, by default). The options are
not case sensitive.
Striping=[on/off]
-----------------
- default is off
This option specifies whether a file is a striped file.
MaxStripeSize=n
---------------
- default for n is - 1 Gigabyte (1073741824 bytes)
- minimum is 65536
- maximum is as default
This option specifies the maximum size in bytes of an
individual stipe.
MaxStripeFiles=n
----------------
- default for n is 16
- minimum is 1
- maximum is 99
This option specifies the number of stripe files, not including
the base file. By default, 17 files are created, the base file
and 16 stripes.
MaxStripeDigits=n
-----------------
- default for n is 2
- minimum is 1
- maximum is 5
This option specifies the number of digits to be appended to the
name of the base file when naming the stripes. For example,
2 would give test01.dat and 5 would give test00001.dat or
tes0001.dat depending on the filename limitations of the operating
system.
Stripe-x=path,n
---------------
- default is not enabled
- x is the stripe number
- path is an alternate path to the stripe
- n is the size to be allocated for this stripe. This size will
remain the default of subsequent stripes until another stripe-x.
This option specifies an alternate path and size for a stripe file.
Once set, the new path and size apply to all stripes until changed by
another Stripe-x option. The number following Stripe- is the
stripe number and must not be prefixed by a 0 character.
Example 1
test.dat has 2 stripes, each of the same size:
[test.dat]
Striping=on
Stripe-1=dir2
Stripe-2=dir3
This causes test.dat to be in the current directory, test01.dat
to be in dir2 and test02.dat to be in dir3.
Example 2
test.dat has 5 stripes:
[test.dat]
Striping=on
Stripe-0=dir1 (this is the path for the base file + stripes 1 to 3)
Stripe-4=dir2
This causes test.dat to be in dir1, test01.dat to be in dir1,
test02.dat to be in dir1, test03.dat to be in dir1,
test04.dat to be in dir2 and test05.dat to be in dir2.
Example 3
test.dat has 3 stripes:
[test.dat]
Striping=on
Stripe-0=dir1,100000000
Stripe-1=dir2,200000000
This causes test.dat to be in dir1 with a file size of 100000000 bytes
and test01.dat to be in dir2 with a file size of 200000000 bytes.
==================================================================
Micro Focus is a registered trademark of Micro Focus Limited.
Micro Focus COBOL is a trademark of Micro Focus Limited.
Windows and Windows NT are trademarks of Microsoft Corporation.
IBM, OS/2 and AIX are registered trademarks of International
Business Machines Corporation.
UNIX is a registered trademark of X/Open Company Limited.
==================================================================
@(#)Vrn/callfh/13Sep96/nrV
Copyright (C) 1996 Micro Focus Limited