ChorusOS man pages section 1M: System Management Utilities

disklabel(1M)

NAME

disklabel- read and write disk pack label

SYNOPSIS

disklabel

-r

disklabel

-w

-r

DESCRIPTION

disklabel is a target utility.

The disklabel command can be used to install, examine or modify the label on a disk drive or pack. When writing the label, it can be used to change the drive identification, the disk partitions on the drive, or to replace a damaged label.

There are two forms of the command that read (display), install, or rewrite the label on a disk. Each form has an additional option, -r , which causes the label to be read from or written to the disk directly, rather than going through the system's in-core copy of the label. This option may allow a label to be installed on a disk without kernel support for a label, such as when labels are first installed on a system. It must be used when first installing a label on a disk. The specific effect of -r is described under each command.

The first form of the command (read) is used to examine the label on the named disk drive (for example, sd0 or /dev/rsd0c). It will display all of the parameters associated with the drive and its partition layout. Unless the -r flag is set, the kernel's in-core copy of the label is displayed; if the disk has no label, or the partition types on the disk are incorrect, the kernel may have constructed or modified the label. If the -r. flag is set, the label from the raw disk will be displayed rather than the in-core label.

The second form of the command, with the -w flag set, is used to write a standard label on the designated drive. The required arguments to disklabel are the drive to be labelled (for example, sd0), and the drive type as described in the disktab (4CC) file. The drive parameters and partitions are taken from that file. If different disks of the same physical type are to have different partitions, it will be necessary to have separate disktab entries describing each, or to edit the label after installation as described below. The optional argument is a pack identification string, up to 16 characters long. The pack id must be quoted if it contains blanks.

If the -r flag is set, the disk sectors containing the label and bootstrap will be written directly. A side-effect of this is that any existing bootstrap code will be overwritten and the disk rendered unbootable for any kind of operating system. If -r is not specified, the existing label will be updated via the in-core copy and any bootstrap code will be unaffected. If the disk does not already have a label, the -r flag must be used. In either case, the kernel's in-core label is replaced.

When updating the label, disklabel first tries to detect any existing valid DOS partitions on the disk. If any are found, disklabel notifies the user and asks for confirmation. This confirmation can be suppressed by using the -y argument (assuming a yes response) or -n argument (assuming a no response) to all questions. These arguments allow disklabel to be run in an unattended mode.

FILES

/etc/disktab

EXAMPLES

disklabel sd0

Display the in-core label for sd0 as obtained via /dev/rsd0c.

disklabel -w -r /dev/rsd0c sd2212 foo

Create a label for sd0 based on information for ``sd2212'' found in /etc/disktab. Any existing bootstrap code will be clobbered.

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE	ATTRIBUTE VALUE
Interface Stability	Evolving

DIAGNOSTICS

The kernel device drivers will not allow the size of a disk partition to be decreased, or the offset of a partition to be changed, while it is open. Some device drivers create a label containing a single large partition if a disk is unlabeled; the label must therefore be written to the ``a'' partition of the disk while it is open. This sometimes requires the desired label to be set in two steps, and the second setting the label on the new partition while shrinking the ``a'' partition.

The newfs(1M) utility will disallow creation of filesystems on FS_BOOT partitions.

BUGS

When a disk name is given without a full pathname, the constructed device name uses the ``c'' partition.

RESTRICTIONS FOR ChorusOS

Originally, this utility was able to install bootstrap code. Options related to bootstrap installation (-B, -b -s) are not supported in this version.

Restoring labels is not supported (-e option).

The -N option which prevents a new label being written on the disk is not supported. The reverse option -W which allows a new label to be written on the disk when a previous label was in read-only mode is not supported.

ChorusOS 4.0 Last Revised December 1999