This article contains best practices for setting the iSCSI Service (open-iscsi) to start automatically in XenServer.

Instructions

Complete the following procedure:

1. Set open-iscsi service run level to On:
   # chkconfig --list (list all services)
   # chkconfig --list open-iscsi (list iscsi service) 
   # chkconfig open-iscsi on (sets service to always run automatically)
   # chkconfig open-iscsi off (sets service to not always run automatically)

   You should get these options when set to run automatically

   # chkconfig --list open-iscsi
   open-iscsi     0:off 1:off 2:on 3:on 4:on 5:on 6:off 

2. Enable automatic startup in iscsid.conf file by editing the /etc/iscsi/iscsid.conf file and uncommented:
   node.startup = automatic

   And commented:

   # node.startup = manual

3. Enable automatic startup in the node iqn IP address default file:

   /etc/iscsi/nodes/iqn.1992-08.com.netapp:sn.135027806/10.12.45.10,3260,2000/default
   [root@ftlchristophxen41a 10.12.45.10,3260,2000]# more default
   node.name = iqn.1992-08.com.netapp:sn.135027806
   node.tpgt = 2000
   node.startup = automatic
   iface.hwaddress = default
   iface.iscsi_ifacename = default
   iface.net_ifacename = default
   iface.transport_name = tcp
   node.discovery_address = 10.12.45.10
   node.discovery_port = 3260
   node.discovery_type = send_targets
   node.session.initial_cmdsn = 0
   node.session.initial_login_retry_max = 4
   node.session.cmds_max = 128
   node.session.queue_depth = 32
   node.session.auth.authmethod = None
   node.session.timeo.replacement_timeout = 144
   node.session.err_timeo.abort_timeout = 10
   node.session.err_timeo.reset_timeout = 30
   node.session.iscsi.FastAbort = No
   node.session.iscsi.InitialR2T = No
   node.session.iscsi.ImmediateData = Yes
   node.session.iscsi.FirstBurstLength = 262144
   node.session.iscsi.MaxBurstLength = 16776192
   node.session.iscsi.DefaultTime2Retain = 0
   node.session.iscsi.DefaultTime2Wait = 2
   node.session.iscsi.MaxConnections = 1
   node.session.iscsi.MaxOutstandingR2T = 1
   node.session.iscsi.ERL = 0
   node.conn[0].address = 10.12.45.10
   node.conn[0].port = 3260
   node.conn[0].startup = automatic
   node.conn[0].tcp.window_size = 524288
   node.conn[0].tcp.type_of_service = 0
   node.conn[0].timeo.logout_timeout = 15
   node.conn[0].timeo.login_timeout = 15
   node.conn[0].timeo.auth_timeout = 45
   node.conn[0].timeo.active_timeout = 5
   node.conn[0].timeo.idle_timeout = 60
   node.conn[0].timeo.ping_timeout = 5
   node.conn[0].timeo.noop_out_interval = 10
   node.conn[0].timeo.noop_out_timeout = 15
   node.conn[0].iscsi.MaxRecvDataSegmentLength = 131072
   node.conn[0].iscsi.HeaderDigest = None,CRC32C
   node.conn[0].iscsi.DataDigest = None
   node.conn[0].iscsi.IFMarker = No
   node.conn[0].iscsi.OFMarker = No

4. Enable automatic startup in the send_tragets IP address st_config file.

   /etc/iscsi/send_targets/10.12.45.10,3260/st_config
   [root@ftlchristophxen41a 10.12.45.10,3260]# more st_config
   discovery.startup = automatic
   discovery.type = sendtargets
   discovery.sendtargets.address = 10.12.45.10
   discovery.sendtargets.port = 3260
   discovery.sendtargets.auth.authmethod = None
   discovery.sendtargets.timeo.login_timeout = 15
   discovery.sendtargets.reopen_max = 5
   discovery.sendtargets.timeo.auth_timeout = 45
   discovery.sendtargets.timeo.active_timeout = 30
   discovery.sendtargets.timeo.idle_timeout = 60
   discovery.sendtargets.iscsi.MaxRecvDataSegmentLength = 32768

Readme from open-iscsi.org