A disk used by the operating system for performing I/O operations is divided into contiguous areas called partitions. A partition can be used as a file system area provided by the operating system or as a HiRDB file system area. The following figure shows the relationship between HiRDB file system areas and file system areas provided by the OS.

Figure 6-1 Relationship between HiRDB file system areas and file system areas provided by the OS

(a) UNIX edition

HiRDB file system areas can be created in character special files or in regular files.

In the case of Linux, block special files can also be used. HiRDB handles block special files in the same way as character special files. If you are using block special files, note that references to character special files in this manual also apply to block special files.

Data is input to or output from regular files via the kernel buffer. By contrast, data is input to or output from character special files directly from the HiRDB buffer. Although the use of character special files is assumed for most cases, regular files provide higher performance in the following cases:

• HiRDB file of an RDAREA storing a table that normally involves a large-volume search
• Work table files

Note, however, that regular files are not robust against system failures. Therefore, the following files must be created in character special files:

• System log files
• Synchronization point dump files
• Status files
• HiRDB files that comprise a system RDAREA
• HiRDB files that comprise a user RDAREA that is updated frequently

Furthermore, when you use the system switchover facility, use character special files for the HiRDB file system areas to be created on a shared disk device. If you use regular files, the updated content might be lost when a system switchover occurs. Even with character special files, you can improve their large-volume search performance by using the prefetch facility.

(b) Windows edition

The HiRDB file system areas are created in Windows partitions.

Normal Windows files

Create a HiRDB file system area by creating files in a normal partition provided by Windows. To do this, use the pdfmkfs command.

Direct disk access (raw I/O)

You can use not only normal partitions but also Windows' direct disk access (raw I/O) to create HiRDB file system areas. The latter uses the raw I/O facility. The raw I/O facility lets you access partitions and logical drives in the same manner as files. When the raw I/O facility is used, HiRDB is no longer affected by Windows file caching operations. Therefore, you can maintain stable performance by, for example, controlling global buffers. However, some of the HiRDB file system areas cannot be created with raw I/O. To use the raw I/O facility, you need to provide unformatted partitions. In Windows, you can create partitions from the window displayed by choosing Computer Management and then Disk Management.

For details about how to create HiRDB files systems with the raw I/O facility, see the HiRDB Version 9 Installation and Design Guide.

We recommend that you create the types of HiRDB files system areas listed and described in the table below. For details about how to design the various HiRDB file system areas, see the HiRDB Version 9 Installation and Design Guide.

Table 6-2 Type of HiRDB file system area

Type of HiRDB file system area	Option#	Description
RDAREA	DB	HiRDB file system area in which RDAREAs (other than list RDAREAs) are stored. This area is always needed.
Shared RDAREA	SDB	HiRDB file system area in which shared RDAREAs are created. This area is needed if you use shared RDAREAs.
System file	SYS	HiRDB file system area in which system log files, synchronization point dump files, and status files are stored. This area is always needed.
Audit trail file		HiRDB file system area in which audit trail files are created. This area is needed to use the security audit facility.
Work table file	WORK	HiRDB file system area in which work table files are stored. This area is always needed.
Utility	UTL	HiRDB file system area in which files used by utilities (backup files, unload data files, unload log files, index information files, or differential backup management files) are created. Windows edition only: The Windows cache is not used. About HiRDB file system areas created in HiRDB versions earlier than 09-50 If a HiRDB file system area was created using NUTL, no change exists in behavior in version 09-50 and later. If a HiRDB file system area was created using UTL, the Windows cache is not used in version 09-50 and later.
	NUTL	Windows edition only: This specification is for compatibility with versions of HiRDB earlier than 09-50. Specifying NUTL is handled as equivalent to specifying UTL.
List RDAREA	WORK	HiRDB file system area in which list RDAREAs are stored. This area is needed to perform narrowed searches.

#: The value of the -k option specification that is specified when you create a HiRDB file system area with the pdfmkfs command.

The pdfmkfs command is used to create a HiRDB file system area.

Reference note

If you use either of the following environment setup support tools the first time you install HiRDB, a HiRDB file system area will be created based on the information you enter:

• Simple setup tool
• Batch file (SPsetup.bat) (Windows edition only)

For details about designing and creating HiRDB file system areas, see the HiRDB Version 9 Installation and Design Guide.

The following table shows the maximum size of HiRDB file system areas.

Table 6-3 Maximum size of a HiRDB file system area

HiRDB type	File type	HiRDB file system area maximum size (MB)
HP-UX edition	Regular file	1,048,575
	Character special file
Solaris edition	Regular file	1,048,575
	Character special file
AIX edition	Regular file (JFS)	65,411
	Regular file (JFS2)	1,048,575
	Character special file
Linux edition	Regular file	1,048,575
	Character special file
Windows edition	Normal Windows file	1,048,575
	Direct disk access (raw I/O)