4.3.2 Creating a HiRDB file system area using the raw I/O facility

You can create a HiRDB file system area that uses Windows's direct disk access (raw I/O) capabilities, which access partitions or logical drives in the same manner as files. This is called the raw I/O facility. If you use the raw I/O facility, HiRDB will no longer be affected by Windows file cache operations. For that reason, you can maintain stable performance by using means such as global buffer management.

Organization of this subsection
(1) Support range of the raw I/O facility
(2) Preparing to use the raw I/O facility

(1) Support range of the raw I/O facility

The following table shows the range of HiRDB file system areas supported by the raw I/O facility:

Purpose#1Support
DBS
SDBS
SYSS
WORKS
UTLB
SVRS
NUTL#2S

S: The raw I/O facility is supported.

B: The raw I/O facility is not supported.

#1: This is the purpose of the HiRDB file system area that is specified with the -k option of the pdfmkfs command.

#2: The following utility files support the raw I/O facility:
  • Backup files
  • Unload log files
  • Unload data files
  • Differential backup management files
  • Index information files

(2) Preparing to use the raw I/O facility

Using the raw I/O facility requires the preparations described below prior to executing the pdfmkfs command.

(a) Disks

The raw I/O facility allocates a single drive to a single HiRDB file system area. In this case, each drive must comprise a single disk. Since a single disk means a volume that is viewed by the OS as a single storage area, a hardware RAID can be used, but a software RAID, in which a single drive is made up of multiple disks, cannot.

Drives that can use the raw I/O facility must be hard disks with 512-byte sectors.

The table below lists HiRDB support for different combinations of disk type and partition style.

Disk typePartition styleSupport
32-bit mode HiRDB64-bit mode HiRDB
Basic diskMBR (master boot record)YY
GPT (GUID partition table)NY
Dynamic diskMBR (master boot record)NN
GPT (GUID partition table)NN
Legend
Y: Supported
N: Not supported

(b) Creating partitions and logical drives

To use the raw I/O facility, prepare an unformatted partition or logical drive. A single drive must be comprised of a single primary partition or a single logical drive.

Create the partition by choosing Windows Computer Management, and then Disk Management. Specify a partition size larger than the size of the HiRDB file system area. Note, however, that too large a partition size can waste space.

Assign a drive character to the created partition.

For details about creating partitions or logical drives and about assigning drive characters, see Help for Windows Disk Management.