Symptoms:
Post upgrading VC to 7.0 u3h, when trying to configure the backup on VAMI it fails with the error "Access to backup server is denied. Check your credentials"
Checked applmgmt.log
2023-02-24T00:00:03 AM AEDT [3096]INFO:plugins.SMBClientStorageIOLib:Running Command: ['/usr/bin/smbclient', '//backupserver.vsphere.local/backup_share/', '-A', '/dev/shm/smbCredentialFile8begk_do', '--send-bu ffer', '100M', '-c', 'cd files/backup/vxrail/vCenter/vcsa1.vsphere.local/; ls'] 2023-02-24T00:00:04 AM AEDT [3096]ERROR:plugins.SMBClientStorageIOLib:Command failed with error: NT_STATUS_LOGON_FAILURE 2023-02-24T00:00:04 AM AEDT [3096]ERROR:vmware.appliance.backup_restore.archive_impl:Failed to enumerate archive info. Url smb://backupserver.vsphere.local/backup_share/files/backup/vxrail. Err [Failure instance: Traceback: <class 'plugins.StorageIOErrorsLib.PluginError'>: Plugin error occurred. ErrCode: 1, Args: () /usr/lib/python3.7/threading.py:926:_bootstrap_inner /usr/lib/python3.7/threading.py:870:run /usr/lib/python3.7/site-packages/twisted/_threads/_threadworker.py:46:work /usr/lib/python3.7/site-packages/twisted/_threads/_team.py:190:doWork
Backup using IP fails with same UI error and NT_STATUS_LOGON_FAILURE in the applmgmt.log
Starting vCenter 7.0 Update 3h build 20395099, the backup architecture has been changed to 'smbclient' from 'cifs' . Limitation of samba client being kerberos DNS TXT packets that are needed for kerberos authentication are not supported.
This causes specific failure in environments where Domain-based DFS namespace is used for the target backup location.