Device alias database

When a fibre channel disk and fiber channel HBA ports join the fabric, they send a FLOGI frame (Fibric Login). The fabric (MDS switch) then assigns an FCID to each fibre channel disk and each fibre channel HBA port. These FLOGI mappings of pWWWN/nWWN to FCID are stored in the FLOGI database.

In order to configure device alias database, I need to know pWWWNs of the HBAs and JBOD drives. show flogi database could tell me pWWWNs of them:


mds9124# show flogi database
--------------------------------------------------------------------------------
INTERFACE        VSAN    FCID           PORT NAME               NODE NAME
--------------------------------------------------------------------------------
fc1/3            1     0xc90000  21:00:00:e0:8b:0a:fc:6d 20:00:00:e0:8b:0a:fc:6d

Total number of flogi = 1.

3rd, 4th and 5th bytes represent OUI (if you look up the OUI value 00:e0:8b on http://www.coffer.com, you could confirm that the HBA is made by Qlogic).

Think of each drive as an individual NL_Port on the Fibre Channel Arbitrated Loop. MDS port connected to HBA must run on TL mode.

The device-aliases have global significance, therefore, we could configure device-alias on one MDS, and later on (when we enable links between MDSes) the device-alias database will be distributed to other MDSes automatically using CFS CW_ILS frame.

We could have two different mode for hte device-alias: basic and enhanced. Enhanced mode is recommended if you are configuring feature SDV(SAN Device Virtualization). In basic mode, device-aliases are referred to by pWWN in the zoning configuration. In enhanced mode, device-aliases are referred to by name. Therefore, if pWWN changes, you don't need  to update zoning configuration.


mds9124# show device-alias status
Fabric Distribution: Enabled
Database:- Device Aliases 0  Mode: Basic
           Checksum: 0xf6bd6b3389b87233d462029172c8612

mds9124# conf t
Enter configuration commands, one per line.  End with CNTL/Z.
mds9124(config)# device-alias mode enhanced
mds9124(config)# show device-alias status
Fabric Distribution: Enabled
Database:- Device Aliases 0  Mode: Basic
           Checksum: 0xf6bd6b3389b87233d462029172c8612
Locked By:- User "CLI/SNMPv3:admin" SWWN 20:00:54:7f:ee:e8:25:80
Pending Database:- Device Aliases 0  Mode: Enhanced

The device-alias configuration is locked. In order to do it active, we should commit the change to CFS:

mds9124(config)# device-alias commit

mds9124(config)# show device-alias status

Fabric Distribution: Enabled

Database:- Device Aliases 0  Mode: Enhanced

           Checksum: 0xb713791d47fd2d205e1a5fa01ea9c447

To change mode to basic:

mds9124(config)# no device-alias mode enhanced

mds9124(config)# device-alias commit

To configure device alias for the Initiator:

mds9124(config)# show device-alias database

There are no entries in the database

mds9124(config)# device-alias database

mds9124(config-device-alias-db)# show flogi database

--------------------------------------------------------------------------------

INTERFACE        VSAN    FCID           PORT NAME               NODE NAME

--------------------------------------------------------------------------------

fc1/3            1     0xc90000  21:00:00:e0:8b:0a:fc:6d 20:00:00:e0:8b:0a:fc:6d

Total number of flogi = 1.

mds9124(config-device-alias-db)# device-alias name Initiator pwwn 21:00:00:e0:8b:0a:fc:6d

mds9124(config-device-alias-db)# exit

mds9124(config)# show device-alias database

There are no entries in the database

mds9124(config)# device-alias commit

mds9124(config)# show device-alias database

device-alias name Initiator pwwn 21:00:00:e0:8b:0a:fc:6d

Total number of entries = 1

mds9124(config)#

Because my link between mds9124 and mds9506 is up, without any further configuration, we got:

mds9506# show device-alias database

device-alias name Initiator pwwn 21:00:00:e0:8b:0a:fc:6d

Total number of entries = 1

Fcaliases are not supported by CFS distribution, therefore you have to configure them on every MDS manually. Fcaliases have logical scope (VSAN-based), support multiple members, you can use identifiers other than pWWN:

mds9124(config)# fcalias name TestFcalias vsan 1

mds9124(config-fcalias)# member ?

  device-alias       Add device-alias member to fcalias

  domain-id          Add member based on domain-id,port-number

  fcid               Add FCID member to fcalias

  fwwn               Add Fabric Port WWN to fcalias

  interface          Add member based on interface

  ip-address         Add IP address member to fcalias

  pwwn               Add Port WWN to fcalias

  symbolic-nodename  Add Symbolic Node Name to fcalias

mds9124(config-fcalias)# member pwwn  50:0a:09:82:99:9b:48:e0 ?

  <CR>

  both       Enter device-type as both

  initiator  Enter device-type as initiator

  lun        Add PortWWN-LUN member to fcalias

  target     Enter device-type as target

mds9124(config-fcalias)# member pwwn  50:0a:09:82:99:9b:48:e0

mds9124(config-fcalias)# show fcalias vsan 1

fcalias name TestFcalias vsan 1

  pwwn 50:0a:09:82:99:9b:48:e0 [Initiator]

Since fcalias does not support CFS, we do not have this information on the second MDS:

mds9506# show fcalias vsan 1

Alias not present

We can import fcalias into device-alias database:

mds9124(config)# device-alias import fcalias vsan 1

mds9124(config)# device-alias commit

Now we do see this information on seconds MDS:

mds9506# show device-alias database

device-alias name Initiator pwwn 21:00:00:e0:8b:0a:fc:6d

device-alias name TestFcalias pwwn 50:0a:09:82:99:9b:48:e0

Total number of entries = 2