HP StoreEver Tape Libraries Failover User Guide (5697-3323, June 2014)

path. The following example shows the command for a specific path and the commands may be
directed at any path by replacing the device identifier with the identifier from the sg or st device.
For example, a command executed on pfo3 will report information for the device at sg3 and
st3.
Viewing the current driver revision
The driver revision number indicates the build date of the driver and can be viewed by running:
cat /proc/scsi/sg/version
Viewing device status
You can view the status of a device that is controlled by the failover driver by reading a file in the
/sys file system. For example, to see the path status for /dev/sg3:
cat /sys/class/pfo/pfo3/paths
Terms
active_drive A path to a tape library via an advanced path failover active drive.
down The driver is aware of this path, but if the driver attempted to use this path at
this time it would fail and another path would need to be chosen.
last The path that the driver was most recently able to successfully perform a SCSI
command on. This is probably the path that will be used next. There are no
/dev files open to this device.
open The path that the driver was most recently able to successfully perform a SCSI
command on. This is probably the path that will be used next. There is at least
one /dev file open to this device.
prefer The driver will attempt to send the commands on this path after the next device
file open() call. This path will override the last known good path.
session_key The identifier number of the open session, in hexadecimal.
wwnn World-wide node name of the device.
wwpn World-wide port name of the Fibre Channel port on the device.
44 Installing and using Linux advanced path failover drivers