HP 3PAR SUSE Linux Enterprise Implementation Guide

SCSI layer will still perform CRC error recovery at the session level rather than at the PDU
level.
CAUTION: Enabling Header and Data Digest will cause some I/O performance degradation
due to data checking.
You can enable the Header and Data Digest by adding the following lines in iSCSI
configuration file /etc/iscsi/iscsid.conf:
node.conn[0].iscsi.HeaderDigest = CRC32C
node.conn[0].iscsi.DataDigest = CRC32C
NOTE: In order for the parameters changes to take effect, run the iSCSI service after the
change.
9. Enable any other configuration changes such as CHAP authentication. For details, see “Setting
the Host CHAP Authentication on the HP 3PAR StoreServ Storage” (page 41).
Configuring SUSE iSCSI Settings with Device-mapper Multipathing
The /etc/multipath.conf file is used by Device-mapper where the multipathing parameters
have been set. The default installed /etc/multipath.conf file must be edited with the following
changes for a minimum configuration connecting to an HP 3PAR StoreServ Storage array. Entries
listed in multipath.conf override the default kernel parameters for dm-multipath. In general,
the kernel defaults are sufficient with the exception of the devices entries for HP 3PAR.
NOTE: Refer to the SUSE Enterprise Linux Server Storage Administration Guide and online docs
in the /usr/share/doc/packages/multipath-tools folder.
1. Remove or comment out all entries in the /etc/multipath.conf file except for the devices
files of devices currently in use.
2. Edit the device structure to add entries for the HP 3PAR array and remove other product entries
that are not needed. See “Modifying the /etc/multipath.conf File” (page 31).
The partitions for the multipath devices are started at host bootup and enabled when the
multipathd daemon runs the rc script.
3. Verify that the rc script is turned on. The following output shows that it is enabled for run-level
3, 4 and 5. Enable it appropriately for your configuration:
# chkconfig --list | grep multipath
boot.multipath 0:off 1:off 2:off 3:off 4:off 5:on 6:off
multipathd 0:off 1:off 2:off 3:on 4:off 5:on 6:off
4. Check that the appropriate rc scripts have been created for each run level. The start number(s)
may not match those shown here.
# ls /etc/rc.d/rc3.d/S*multi*
/etc/rc.d/rc3.d/S08multipathd
# ls /etc/rc.d/rc5.d/S*multi*
/etc/rc.d/rc5.d/S01boot.multipath
/etc/rc.d/rc5.d/S08multipathd
5. Use the multipath -v 3 command to obtain more detailed information about Device-mapper
nodes and their associated paths.
See also “Displaying Detailed Device-mapper Node Information” (page 58) for multipath
options.
Configuring SUSE 10 & SUSE 11 for iSCSI 39