Quantum Scalar i6000 User Manual page 368

Chapter 10: Storage Networking
Configuring Control Path Failover
354
World Wide Port Name (WWPN) associated with the selected tape drive.
While the tape drive (SSC device) responds as LUN 0 at the WWPN, the
partition media changer (SMC device) responds as LUN 1 at the WWPN.
For example, consider such a drive configured to host the library control
path. A switch could detect the tape drive as LUN 0 with WWPN
500308c0:9e2c3001 and detect the media changer as LUN 1 with
WWPN 500308c0:9e2c3001 also via switch port 1:
[11:0:0:0] tape
st0 /dev/sg2
[11:0:1:1] mediumx
dev/sg3
If two drives are configured for library control path failover
functionality, then the library control path will be able to fail over to the
configured redundant failover drive. In this type of configuration, the
library control path is not hosted by a drive's physical FC port, but via a
virtual port with a unique WWPN, reporting the SMC device also as
LUN 0. Such configuration also requires that the two configured control
path drives (primary and secondary) are connected to the same switch,
which must support N-Port ID Virtualization (NPIV), and that the drives
connect with point-to-point connection topology.
Virtual port WWPNs are based on the library's WWNN and are identified
by the WWPN's last 12 bits. A partition's control path configured via a
virtual port would end in 0x7FF for the first partition, 0x7FE for the
second partition, 0x7FD for the third partition and so on. The partition's
virtual port is presented by only one of the configured failover drives. If
the active path to the media changer fails due to a FC cable issue, a
drive failure or even a drive removal, the library control path will switch
to the secondary drive and appear to the SAN via the same WWPN.
For example, consider two drives configured for control path failover
configured within the first partition. A switch could detect the two tape
drives as LUN 0 with WWPNs 500308c0:9e2c3001 and
500308c0:9e2c3005 at switch ports 1 and 2, and detect the media
changer also as LUN 0 with WWPN 500308c0:9e2c37ff via switch port
1:
[11:0:0:0] tape
st0 /dev/sg2
[11:0:1:0] mediumx
sg3
fc:0x500308c09e2c3001 , 0x010100
fc:0x500308c09e2c3001,
fc:0x500308c09e2c3001 , 0x010100
fc:0x500308c09e2c37ff,
Quantum Scalar i6000 User's Guide
/dev/
0x010101 /
/dev/
0x010101 /dev/