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

Similarly, to find the special files for tape drives, use ioscan -knNfC tape to list the tape drives
and then use ioscan -m lun -H <H/W path> to see information for the drive. For example,
if the LUN hardware path to the tape drive is 64000/0xfa00/0x37:
# ioscan -m lun -H 64000/0xfa00/0x37
Class I Lun H/W Path Driver S/W State H/W Type Health Description
=====================================================================================
tape 29 64000/0xfa00/0x37 estape CLAIMED DEVICE online HP Ultrium 6-SCSI
0/0/0/9/0/0/1.0x50014382c6e4f009.0x0 <— Tape device special file
0/0/0/9/0/0/1.0x50014382c6e4f008.0x0 <— Tape device special file
0/0/0/9/0/0/0.0x50014382c6e4f009.0x0 <— Tape device special file
0/0/0/9/0/0/0.0x50014382c6e4f008.0x0 <— Tape device special file
/dev/rtape/tape29_BEST /dev/rtape/tape29_BESTb /dev/rtape/tape29_BESTn
/dev/rtape/tape29_BESTnb <— Tape device special files
Finding the lockdown path
The load-balance policy used to route data on multiple paths to a tape drive or library is called
the “path-lockdown” policy. Use the scsimgr get_info command to see the current lockdown
path for a library. For example:
# scsimgr get_info -D /dev/rchgr/autoch35
STATUS INFORMATION FOR LUN : /dev/rchgr/autoch38
...
LUN Path used when policy is path_lockdown = 0/0/0/9/0/0/1.0x50014382c6e4f009.0x1000000000000
Use the scsimgr get_attr command to see the current lockdown path for a library. For example:
# scsimgr get_attr -D /dev/rtape/tape28_BEST
SCSI ATTRIBUTES FOR LUN : /dev/rtape/tape28_BEST
...
name = lpt_lockdown
current = 0/0/0/9/0/0/0.0x100000e00222a6c1.0x2000000000000
default =
saved =
For additional information, see the HP-UX man pages: scsimgr (1M), ioscan (1M), mknod
(2), mksf (1M), rmsf (1M).
Troubleshooting advanced path failover
Advanced path failover errors are logged in the /var/adm/syslog/syslog.log file as part
of the default SCSI I/O tracing function of HP-UX. You can use standard file viewing commands,
including cat, vi, dmesg -, and tail -f, to view the syslog.log file.
Enabling or disabling advanced path failover
Advanced path failover is disabled by default. When advanced path failover is disabled, the driver
operates as if the device is not capable of using the advanced path failover feature.
When advanced failover is enabled for the library or tape drive, the device resets itself and must
be opened using the device special file before the driver will recognise it as an advanced path
failover device and use the failover features of the driver. Opening the device is generally done
by the host applications.
You can enable or disable advanced path failover using the library web-based interface. For
instructions, see:
• “Enabling control path failover for the ESL G3” (page 24)
• “Enabling data path failover for the MSL6480” (page 29)
When advanced path failover is disabled, the passive control paths to the library will go into an
error state (NO_HW). in the ioscan (1M) command output. These stale entries do not affect the
function of the library. To clear this errors so the device can be accessed using its device special
file:
50 Installing and using HP-UX advanced path failover drivers