HP 3PAR SUSE Linux Enterprise Implementation Guide

3. Change the time interval to wait for a connection before sending a ping.
node.conn[0].timeo.noop_out_interval = [noop_out_interval]
This allows for more time for the connections that were broken to be re-established before a
ping is sent out (in case of a bad cable or a broken link).
Set this parameter to 10 seconds for a ping to succeed after a connection is made.
node.conn[0].timeo.noop_out_interval = 10
4. To set the host log into the iSCSI nodes every time the iSCSI daemon is started or the host is
rebooted, edit the iSCSI configuration in /etc/iscsi/iscsid.conf and change the values
of the following default settings:
node.startup = automatic
node.conn[0].startup = automatic
NOTE: The node.conn[0].startup variable is optional and not defined in the default
iscsid configuration file.
5. Check the state of the iSCSI service run level with the chkconfig command:
# chkconfig --list | grep iscsi
open-iscsi 0:off 1:off 2:off 3:on 4:off 5:on 6:off
6. Verify that Run level 5 is turned on. If not turned on, issue the following commands:
# chkconfig open-iscsi on
7. Session and device queue depth in /etc/iscsi/iscsid.conf may require tuning
depending on your particular configuration. node.session.cmds_max controls how many
commands the session will queue. node.session.queue_depth controls the device's
queue depth. If you are deploying HP 3PAR’s Priority Optimization software, you may need
to increase or max out the node.session.cmds_max and node.session.queue_depth
values to ensure the host has sufficient I/O throughput to support this feature. For complete
details of how to use Priority Optimization (Quality of Service) on HP 3PAR arrays, see the
HP 3PAR Priority Optimization technical whitepaper, which is available on the following HP
website:
HP 3PAR Priority Optimization
In a multihost-to-single HP 3PAR StoreServ Storage configuration, if one host is using up all
the I/O buffers on the target iSCSI port, you can throttle the host I/O by reducing the
node.session.cmds_max and node.session.queue_depth values.
8. As an option, you can also enable the Header and Data Digest for error handling and recovery
within the connection.
Typically, whenever a CRC error occurs, the SCSI layer tries to recover by disabling the
connection and recovering. However, by enabling the header and data digest, individual
iSCSI PDUs will be retried for recovery for those connections missing the data (CRC Error) or
missing a PDU or sequence number (Header Digest). If the recovery does not occur, then the
low level SCSI recovery will be initiated. The Header and Data Digest is optional since the
38 Configuring a Host with iSCSI