Controlling the SCSI device state

6.10 LPAR mode z/VM guest

You can use the state attribute of the SCSI device to set a SCSI device back online if it was set offline by error recovery.

Before you begin

The FCP device must be online.

About this task

If the connection to a storage system is working but the storage system has a problem, the error recovery might set the SCSI device offline. This condition is indicated by a message like Device offlined - not ready after error recovery.

To find out the current state of the device, read the state attribute:

# cat /sys/bus/scsi/devices/<scsi_host_no>:0:<scsi_id>:<scsi_lun>/state

where:

<scsi_host_no>: is the SCSI host number that corresponds to the FCP device.
<scsi_id>: is the SCSI ID of the target port.
<scsi_lun>: is the LUN of the SCSI device.

The state can be:

running: The SCSI device can be used for running regular I/O requests.
cancel: The data structure for the device is being removed.
deleted: Follows the cancel state when the data structure for the device is being removed.
quiesce: No I/O requests are sent to the device, only special requests for managing the device. This state is used when the system is suspended.
offline: Error recovery for the SCSI device failed.
blocked: Error recovery is in progress and the device cannot be used until the recovery process is completed.

To set an offline device online again, write running to the state attribute.

Procedure

Issue a command of this form:

# echo running > /sys/bus/scsi/devices/<scsi_host_no>:0:<scsi_id>:<scsi_lun>/state

Example

In the following example, SCSI device 1:0:18:1086537744 is offline and is then set online again:

# cat /sys/bus/scsi/devices/1:0:18:1086537744/state
offline
# echo running > /sys/bus/scsi/devices/1:0:18:1086537744/state