How to Disconnect a SCSI Controller

Disconnecting a SCSI device must be done with caution, particularly when you are dealing with controllers for disks that contain critical file systems such as root (/), usr, var, and the swap partition. The dynamic reconfiguration software cannot detect all cases where a system hang might result. Use this procedure with caution.

The following procedure uses SCSI controller c1 in the example of disconnecting a SCSI device.

1. Become superuser.

2. Verify that the device is connected before you disconnect it.

   # cfgadm -al Ap_Id Type Receptacle Occupant Condition c0 scsi-bus connected configured unknown c0::dsk/c0t0d0 disk connected configured unknown c0::rmt/0 tape connected configured unknown c1 scsi-bus connected configured unknown c1::dsk/c1t3d0 disk connected configured unknown c1::dsk/c1t4d0 disk connected configured unknown

3. Disconnect the SCSI controller.

   # cfgadm -c disconnect c1 WARNING: Disconnecting critical partitions may cause system hang. Continue (yes/no)? y

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   Caution –

   This command suspends all I/O activity on the SCSI bus until the cfgadm -c connect command is used. The cfgadm command does some basic checking to prevent critical partitions from being disconnected, but it cannot detect all cases. Inappropriate use of this command can result in a system hang and could require a system reboot.

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4. Verify that the SCSI bus is disconnected.

   # cfgadm -al Ap_Id Type Receptacle Occupant Condition c0 scsi-bus connected configured unknown c0::dsk/c0t0d0 disk connected configured unknown c0::rmt/0 tape connected configured unknown c1 unavailable disconnected configured unknown c1::dsk/c1t3d0 unavailable disconnected configured unknown c1::dsk/c1t4d0 unavailable disconnected configured unknown

   The controller and all the devices that are attached to it are disconnected from the system.