disksecn(1M)

NAME

disksecn — calculate default disk section sizes

SYNOPSIS

disksecn [-p|-d] [-b block_size] [-n disk_name]

DESCRIPTION

disksecn is used to calculate the disk section sizes based on the Berkeley disk partitioning method.

disksecn recognizes the following options:

-p: Produce tables suitable for inclusion in the device driver.
-d: Produce tables suitable for generating the disk description file /etc/disktab.
-b block_size: When generating the above tables, use a sector size of block_size bytes, where block_size can be 256, 512, 1024, or 2048. Defaults to DEV_BSIZE (defined in <sys/param.h>) if not specified.
-n disk_name: Specifies the disk name to be used in calculating sector sizes; for example, hp7912 or hp7945. If an unknown disk name is specified, disksecn prompts the user for the necessary disk information.

If neither -p nor -d table selection switches are specified a default table of the section sizes and range of cylinders used is output.

Disk section sizes are based on the total amount of space on the disk as given in the table below (all values are supplied in units of 256-byte sectors). If the disk is smaller than approximately 44 Mbytes, disksecn aborts and returns the message disk too small, calculate by hand.

Section 44-56MB 57-106MB 107-332MB 333+MB
0 97120 97120 97120 97120
1 39064 39064 143808 194240
3 39064 39064 78128 117192
4 unused 48560 110096 429704
6 7992 7992 7992 7992
10 unused unused unused 516096

Note

It is important to note the difference between the block size passed into disksecn via the -b switch argument and the sector size the user is asked to input when an unknown disk name is passed to disksecn via the -n switch argument.

The block size is the sector size that disksecn assumes the disk to have when it prints the requested tables. All information printed in the tables is adjusted to reflect this assumed sector size (block size) passed in by the user. The sector size requested by disksecn when an unknown disk name is passed does not necessarily have to be the same as the assumed sector size (block size) passed in by the -b switch argument.

For example, a user wants to see the device driver tables for the disk named hp7945 with an assumed sector size (block size) of 256 bytes. The user has the following information about the hp7945 disk:

Disk type = winchester
Sector size = 512
Number of sectors per track (512 byte sectors) = 16
Number of tracks = 7
Number of cylinders = 968
Revolutions per minute = 3600

The user invokes disksecn by typing the following command:

disksecn -p -b 256 -n hp7945 

Assuming that hp7945 is an unknown disk name, disksecn prompts the user for the necessary disk information. The user should input the information as shown above, reflecting a sector size of 512 bytes. All the information will be adjusted within disksecn to reflect the assumed sector size (block size) of 256 bytes, passed as the argument of the -b switch, before the requested device driver table is output.

This adjustment also takes place when the disk name is known and an assumed sector size (block size) is passed in as the argument of the -b switch which is not DEV_BSIZE bytes, the assumed sector size (block size) used to create the etc/disktab file.

RETURN VALUE

disksecn returns the following values:

0: Successful completion.
1: Usage error.
2: User did not input parameters for an unknown disk.
3: Disk too small or an invalid block size.

disksecn aborts and prints an error message under the following conditions:

disksecn was invoked without specifying a disk name.
Requested both -p and -d switch.
Illegal block size requested.
Unknown disk name was specified and user did not supply disk information.
Disk's maximum storage space is less than approximately 44 MB.

WARNINGS

Alternate names are not included in the output when the -d switch is used.

Blanks are required in the command line between each of the switches when invoking disksecn.

A blank is required between the -n switch and the disk name argument to that switch. For example:

disksecn -p -b 1024 -n hp9712 

disksecn does not save the block size used to generate the /etc/disktab disk description file. The system assumes that the block size used was DEV_BSIZE when it reads the information stored in the etc/disktab file.

AUTHOR

disksecn was developed by the University of California, Berkeley.

FILES

/etc/disktab

disksecn(1M)

Technical documentation

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