Install guide

previous method for gathering WWIDs required the execution of the scsi_id command on each LUN.
$ scsi_id -g -s /blo ck/sdc #External LUN, returns
360a9800056724671684a514137392d65
$ scsi_id -g -s /blo ck/sdd #External LUN, returns
360a9800056724671684a502d34555579
The following example of a multipath configuration file shows the Red Hat Cluster Suite quorum disk and,
for the RAC/GFS node, the first of three Oracle Clusterware Voting Disks. This excerpt is the stanza that
identifies the WWID of the LUNS in the m ultipath.conf file.
multipath {
no_path_retry fail
wwid
360a9800056724671684a514137392d65
alias qdisk
}
#The following 3 are voting disks that are necessary ONLY for the RAC/GFS
configuration!
multipath {
no_path_retry fail
wwid
360a9800056724671684a502d34555579
alias vote1
}
multipath {
no_path_retry fail
wwid
360a9800056724671684a502d34555578
alias vote2
}
multipath {
no_path_retry fail
wwid
360a9800056724671684a502d34555577
alias vote3
}
The only two parameters in the mulipath configuration file that must be changed are
path_grouping_policy (set to failover) and path_checker (set to tur). Historically, the
default was to readsector0, or directio, both of which create an I/O request. For voting disks on
highly loaded clusters, this may cause voting “jitter”. T he least invasive path checking policy is TUR
(Test Unit Ready), and rarely disturbs qdisk or Clusterware voting. T UR and zone isolation both
reduce voting jitter. The voting LUNS could be further isolated into their own zone, but this would require
dedicated WWPN pathways; this would likely be more trouble than it is worth.
Some storage vendors will install their HBA driver and also have specific settings for the
m ultipath.conf file, including procedures, defined by the prio_callout parameter. Check with the
vendor.
The following example shows the remaining portion of the m ultipath.conf file.
Chapter 3. Software Installation and Configuration
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