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System Administration Guide: Devices and File Systems

Keywords in the format.dat File

The format.dat file contains disk definitions that are read by the format utility when it is started. Each definition starts with one of the following keywords: disk_type or partition. These keywords are described in the following table.

Table 15–6 Keyword Descriptions for the format.dat File

Keyword 

Description 

disk_type

Defines the controller and disk model. Each disk_type definition contains information that concerns the physical geometry of the disk. The default data file contains definitions for the controllers and disks that the Oracle Solaris OS supports.

You need to add a new disk_type definition only if you have an unsupported disk. You can add as many disk_type definitions to the data file as you want.

partition

Defines a partition table for a specific disk type. The partition table contains the partition information, plus a name that lets you refer to it in the format utility. The default format.dat file contains default partition definitions for several kinds of disk drives. Add a partition definition if you recreated partitions on any of the disks on your system. Add as many partition definitions to the data file as you need.

Disk Type (format.dat)

The disk_type keyword in the format.dat file defines the controller and disk model. Each disk_type definition contains information about the physical geometry of the disk. The default format.dat file contains definitions for the controllers and disks that the Oracle Solaris OS supports. You need to add a new disk_type only if you have an unsupported disk. You can add as many disk_type definitions to the data file as you want.

The keyword itself is assigned the name of the disk type. This name appears in the disk's label, and is used to identify the disk type whenever the format utility is run. Enclose the name in double quotation marks to preserve any white space in the name. The following table describes the identifiers that must also be assigned values in all disk_type definitions.

Table 15–7 Required disk_type Identifiers (format.dat)

Identifier 

Description 

ctlr

Identifies the controller type for the disk type. Currently, the supported values are SCSI and ATA.  

ncyl

Specifies the number of data cylinders in the disk type. This determines how many logical disk cylinders the system will be allowed to access.  

acyl

Specifies the number of alternate cylinders in the disk type. These cylinders are used by the format utility to store information such as the defect list for the drive. You should always reserve at least two cylinders for alternates.

pcyl

Specifies the number of physical cylinders in the disk type. This number is used to calculate the boundaries of the disk media. This number is usually equal to ncyl plus acyl.

nhead

Specifies the number of heads in the disk type. This number is used to calculate the boundaries of the disk media.  

nsect

Specifies the number of data sectors per track in the disk type. This number is used to calculate the boundaries of the disk media. Note that this number includes only the data sectors. Any spares are not reflected in the number of data sections per track.  

rpm

Specifies the rotations per minute of the disk type. This information is put in the label and later used by the file system to calculate the optimal placement of file data.  

Other identifiers might be necessary, depending on the controller. The following table describes the identifiers that are required for SCSI controllers.

Table 15–8 Required disk_type Identifiers for SCSI Controllers format.dat

Identifier 

Description 

fmt_time

Specifies a number that indicates how long it takes to format a given drive. See the controller manual for more information.  

cache

Specifies a number that controls the operation of the on-board cache while the format utility is operating. See the controller manual for more information.

trks_zone

Specifies a number that identifies how many tracks that exist per defect zone, to be used in alternate sector mapping. See the controller manual for more information.  

asect

Specifies a number that identifies how many sectors are available for alternate mapping within a given defect zone. See the controller manual for more information.  

Example 15–1 Required disk_type Identifiers for SCSI Controllers (format.dat)

The following are examples of disk_type definitions:


disk_type = "SUN1.3G" \
        : ctlr = SCSI : fmt_time = 4 \
        : trks_zone = 17 : asect = 6 : atrks = 17 \
        : ncyl = 1965 : acyl = 2 : pcyl = 3500 : nhead = 17 : nsect = 80 \
        : rpm = 5400 : bpt = 44823

disk_type = "SUN2.1G" \
        : ctlr = SCSI : fmt_time = 4 \
        : ncyl = 2733 : acyl = 2 : pcyl = 3500 : nhead = 19 : nsect = 80 \
        : rpm = 5400 : bpt = 44823

disk_type = "SUN2.9G" \
        : ctlr = SCSI : fmt_time = 4 \
        : ncyl = 2734 : acyl = 2 : pcyl = 3500 : nhead = 21 : nsect = 99 \
        : rpm = 5400