chdev Command
Purpose
Changes the characteristics of a device.
Syntax
chdev -dev Name [ -perm ] [ -attr Attribute=Value [ Attribute=Value... ] ]
Description
The chdev command changes the characteristics of
the device specified with the given device logical name (the -dev Name flag). Some changes may not be allowed
when the device is in the Available state.
When the -perm flag is not specified, the chdev command applies the changes to the device and updates the database
to reflect the changes. If the -perm flag is specified,
only the database is updated to reflect the changes, and the device itself
is left unchanged. This is useful in cases where a device cannot be changed
because it is in use; in which case, the changes can be made to the database
with the -perm flag, and the changes will be applied
to the device when the system is restarted. Not all devices support the -perm flag.
Attention: To protect the Configuration database, the chdev command is not interruptible. To stop this command before execution
is complete could result in a corrupted database.
Flags
| -attr Attribute=Value |
Specifies the device attribute value pairs used for
changing specific attribute values. The Attribute=Value parameter can use one attribute value pair or multiple attribute value
pairs for one -attr flag. If you use an -attr flag with multiple attribute value pairs, the list of pairs must
be enclosed in quotes with spaces between the pairs. For example, entering -attr Attribute=Value lists one
attribute value pair per flag, while entering -attr 'Attribute1=Value1 Attribute2=Value2' lists more than one
attribute value pair. |
| -dev Name |
Specifies the device logical name, indicated by the Name parameter, whose characteristics are to be changed. |
| -perm |
Changes the device's characteristics permanently without
actually changing the device. This is useful for devices that cannot be made
unavailable and cannot be changed while in the available state. By restarting
the system, the changes will be applied to the device. Not all devices support
the -perm flag. |
Exit Status
See Virtual I/O Server command exit status.
Examples
- To change the retention instructions of the 4mm SCSI tape drive rmt0 so that the drive does not move the tape to the beginning, then
to the end, and then back to the beginning each time a tape is inserted or
the drive is powered on, type:
chdev -dev rmt0 -attr ret=no
- To change the SCSI ID of the available SCSI adapter scsi0 that cannot be made unavailable or changed due to available disk
drives connected to it, type:
chdev -dev scsi0 -attr id=6 -perm
To
apply the change to the adapter, shutdown and restart the system.
Related Information
The cfgdev command,
the chpath command, the lsdev command, the lsmap command, the lspath command, the mkpath command, the mkvdev command,
the rmdev command, and
the rmpath command.