WWide Port Name are same for both Port A and Port B in MSL 2024 G3 Series

[itlicense]

I was trying to connect MSL 2024 Tape Library to two different SAN Switch. One set of Drive ports (Port A from Drive 1 and Drive 2) are already connected to QLOGIC SAN Switch and Second ser of port (Port B from Drive 1 and Drive 2) are connected to brocade SAN Switch. 

The port B is not visible in Brocade switch so i login to Tape console where i found that both port A and Port B of Drive 1 has same WWN Number. 

As my understanding each fible port should have unique WWN number then how this library sharing the same number for both ports. 

I have attached picture as well.

[Torsten.]

AFAIR for this lib model redundancy works only to a single fabric.

[Curtis_Ballard]

What you are seeing is not correct.  Port B should have an address that is one higher than Port A just like Port A has an address one higher than the drive worldwide node name.  The library starts numbering drive two correctly, skipping the value that should have been assigned to drive one port B.

Can you log into the library network administration console as administrator and select:

Support->Library Logs

Then in that screen select "Save Service Dump" and save that off to a file then copy/paste the text from that file into a posting here?  That will provide information that I can pass on to the engineering team.

I'm not certain if this is related to the drive not showing up on the Brocade switch, that switch shouldn't get confused as long as only one drive port is connected, but it could cause problems at any host that is connected to both switches.

Do you have software on the host that supports Multi-Path tape libraries? 

[Curtis_Ballard · Accepted solution]

After a bit more looking I think we understand what is going on.  It looks like the Basic Path Failover feature is enabled in the library.  The behavior you are seeing is normal for that case.  With Basic Path Failover the drive only fully enables one port and the second port is turned on just enough to detect that it has a link to a switch but not enough for the switch to detect the drive. If the link to the first port fails then the drive automatically completes bringing up the second link with the exact same port name as the first port and Fibre Channel features that were designed to detect a cable being moved will detect the change and automatically reconnect to the tape drive over the second port.

Note that when using the basic path failover feature the recommended configuration is to connect both paths to the same switch at least at the first switch behind the host.  That way the switch hides the change from the host.  Some dual port HBAs can also handle the cable change but HPE doesn't test that configuration so I don't recall which dual port HBAs work and which don't work.  If two SANs are used and the HBA doesn't handle the device move detection then the operating system will see the tape drive disappear and come back at a different spot.  Some operating systems and software can handle that OK, some can't.

You can easily test how things will work by just pulling the cable from the port that is active and see if your server can still talk to the tape drive.

[itlicense]

after i disable "Data Path Failover Enabled" option from configuration, i managed to discover WWN number in both sam switch,