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Cisco UCS FCoE SAN boot issue

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Introduction


SAN boot feature allows connected servers to boot using data/image stored in a SAN array rather then in the server local disk. In Cisco UCS servers you can configure a boot policy to boot one or more servers from an operating system image on the SAN. The boot policy can include a primary and a secondary SAN boot. If the primary boot fails, the server attempts to boot from the secondary. This document explains a scenario where a server connected to MDS switch is unable to boot from SAN.

 

 

Issue


The setup consists of Server --(fc)--> MDS --(fc)--> Storage. The flogi from both, the server and the storage, can be seen on the MDS switch and both are zoned correctly; but the fcns database does not seem to be correct. Also the field "scsi-fc:init" for the server is blank, but the storage can be seen as “scsi-fcp:target”.

 

MDS-1# sh zones ac
zoneset name zs_vsan100 vsan 100
  zone name zone_vsan100 vsan 100
  * fcid 0xec0003 [pwwn 50:00:1f:e1:50:09:0c:89]
    pwwn 20:00:00:25:b5:00:00:01
  * fcid 0xec0004 [pwwn 20:00:00:25:b5:00:00:02]
    pwwn 20:00:00:25:b5:00:00:03
    pwwn 20:00:00:25:b5:00:00:04
 
MDS-1# sh flogi data
---------------------------------------------------------------------------
INTERFACE  VSAN    FCID            PORT NAME               NODE NAME      
---------------------------------------------------------------------------

fc1/2      100   0xec0001  20:42:00:05:73:d8:80:c0  20:64:00:05:73:d8:80:c1    
fc1/2      100   0xec0004  20:00:00:25:b5:00:00:02  20:00:00:25:b5:00:00:03    <------ Server
fc1/10     100   0xec0003  50:00:1f:e1:50:09:0c:89  50:00:1f:e1:50:09:0c:80      <------ Storage

MDS-1# sh fcns data

VSAN 100:
--------------------------------------------------------------------------
FCID        TYPE  PWWN                    (VENDOR)        FC4-TYPE:FEATURE
--------------------------------------------------------------------------
0xec0001    N     20:42:00:05:73:d8:80:c0                   npv
0xec0003    N     50:00:1f:e1:50:09:0c:89                    scsi-fcp:target 244
0xec0004    N     20:00:00:25:b5:00:00:02                 

 

Description


The server can not boot from SAN as it can't find the LUN. After further examination, if the server is booted from an installer CD, the server field “scsi-fc:init” can be seen in the show output. The server, in this case UCS, is running in End Host mode and the MDS switch is configured for NPIV. UCS fabric A and B are using different VSAN's; VSAN 100 and VSAN 200.

 

MDS-1# sh fcns  data  

VSAN 100:
--------------------------------------------------------------------------
FCID        TYPE  PWWN                    (VENDOR)        FC4-TYPE:FEATURE
--------------------------------------------------------------------------
0xec0000    N     20:43:00:05:73:d8:80:c0                     npv
0xec0001    N     20:42:00:05:73:d8:80:c0                     npv
0xec0003    N     50:00:1f:e1:50:09:0c:89                      scsi-fcp:target 244
0xec0004    N     20:00:00:25:b5:00:00:02                

Total number of entries = 4

VSAN 200:
--------------------------------------------------------------------------
FCID        TYPE  PWWN                    (VENDOR)        FC4-TYPE:FEATURE
--------------------------------------------------------------------------
0xea0000    N     20:44:00:05:73:d8:56:40                     npv
0xea0001    N     20:43:00:05:73:d8:56:40                     npv
0xea0002    N     50:00:1f:e1:50:09:0c:8d                      scsi-fcp:target 244
0xea0006    N     20:00:00:25:b5:00:00:0d         

 

Resolution


In the above scenario the zoning is done with vhba initator pwwn and storage target. The reason we don't see the lun, must be the lun masking / mapping. The fcns/flogi is correct, as well as zoning. Also some issue with the storage array, after a crash and rebuild, can cause it to be visible to the network but not present any LUN to the servers.

 

 

Related Information


UCS SAN Troubleshooting
Cisco UCS Manager GUI Configuration Guide
FCoE boot from UCS B200