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How to troubleshoot when LUNs are missing from ESXi Server Environment

Problem DescriptionLUNs are reported as missing in ESXi Server Storage Adapter.Common symptoms encountered are:CHAP Secret MismatchAccess Control List(ACL) was not properly set to LUNMasking the LUN Path from ESXi Host through HBA Adapter. This may prevent ESXi Host from accessing storage devicesTroubleshooting LUNsWe have to undertake some preliminary, pre-requisite troubleshooting steps to ensure that LUN missing is not due to the above mentioned three scenarios:Link Connectivity b/w ESXi Host and Storage SubsystemLink Connectivity verification using vmkping commandAvailable of ESXi HBA Adapter [ in online state] using esxcli iscsi adapter list commandNote: Ensure that the HOST ID on the array for the LUN (on ESX it shows up under LUN ID) is less than 255. Any LUN that has a HOST ID greater than 255 may not be shown under ESXi Host Storage Adapters.i. Available device list from ESXi HBA Adapter [using esxcli storage core device list command – This should not go beyond 254+2[ local device and CD Drive ]Now that we’re done with the preliminary steps, we can move on troubleshooting in case of the scenarios as mentioned above.Case 1: CHAP Secret MismatchCheck for CHAP Secret configuration from Storage Sub System and ensure that the same settings are configured from ESXi/ESX Hosts too. In case it differs, LUN Discover operation will fail, leading to LUN Missing issue.Trouble Shooting Steps:a. tail -f /var/log/syslog.logNote: If you see the message like “Login failed” or “Login Authentication failed”, please go ahead and verify the CHAP Secret Settings on both Storage Subsystem and ESXi Host Storage Adapter.Chap Secret Verification CLI Commands on ESXi Host:b.esxcli iscsi adapter auth chap get –adapter vmhba37c. esxcli iscsi adapter auth chap set –adapter vmhba37 –direction=uni –authname=”chap” –level=required –secret=”password”Chap Secret Verification through vCenter Client on ESXi Host:Navigate to: Configuration tab -> ‘Storage adapters’Select the software adapterClick property and click chap buttonCase 2: Access Control List (ACL) was not properly set to LUNOn the Storage Subsystem, please ensure that the LUN IQNs and access control list (ACL) set to allow the ESXi/ESX Host HBAs to access the iSCSI Targets.Trouble Shooting Steps:1.Run the following commandsa. vol –list (ClientName cmdlet) //This may vary among hardware vendorsb. Vol –info test1 //This may vary among hardware vendorsNote :1.‘*’ in Initiator Group means unrestricted access2.Specific IQN value of Initiator must be added into the LUN iSCSI Initiator Group Creation:Adding Initiator to the Initiator Group:ACL Update on LUNCase 3: Masking the LUN Path from ESXi Host through HBA AdapterNote: Ensure that there is no claim rule set for ESXi Host, which affects LUN Mapping.Trouble Shooting Steps1.Run the following commands in the ESXi Hosta) esxcli storage core claimrule listb) esxcli storage core claimrule remove –rule 101Note: Remove unwanted rules using above commandTroubleshooting the network issue using tcpdump with the below mentioned arguments:“tcpdump-uw -w /tmp/t.cap port 3260 -i vmk1”Happy Troubleshooting..!

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