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Required Adapter and Server OS Settings
115 Dell EMC Storage Compatibility Matrix for SC, PS, and FS Series Arrays | DSCM
# multipathd –k"show config"
To avoid confusion and as a best practice, it is recommended to always explicitly define the SC Series
storage in /etc/multipath.conf. The following example show multipath configuration for SC Series
volumes on RHEL 6 and newer. Please note that these configurations apply only in FC and iSCSI
implementations. The SAS multipath configuration is discussed in section A.2.3.5 and should be used
instead in SAS implementations.
defaults {
user_friendly_names yes
find_multipaths yes
}
devices {
device {
vendor "COMPELNT"
product "Compellent Vol"
path_grouping_policy multibus
path_selector "service-time 0" # See note below
path_checker tur
features "0"
hardware_handler "0"
prio const
failback immediate
rr_weight uniform
no_path_retry queue
}
}
Note: "round-robin 0" is the default for RHEL 6 and older. "service-time 0" is the default for RHEL 7
and newer. Both are acceptable values for SC Series FC/iSCSI volumes.
Once the configuration file is in place, reload multipathd with the updated configuration.
# multipath -r
# multipath –ll
A.2.3.4 iSCSI timeout for multipath environments
The pre-configured iSCSI settings, defined in /etc/iscsi/iscsi.conf, work with SC Series storage
system when the Linux system is also configured to use dm-multipath. It is a best practice to use dm-
multipath for path redundancy and failover. It is important to note the following timeout settings because
they directly affect the storage availability and failure recovery for a SAN storage system. When a SC Series
storage system controller fails, services and volumes fail over to the surviving controller and this failover might
take up to 60 seconds. Therefore ensure the iSCSI timeout settings are sufficient to accommodate this kind of
events. These pre-configured timeout settings, listed below, work well with SC Series storage systems.
• node.conn[0].timeo.noop_out_interval = 5
• node.conn[0].timeo.noop_out_timeout = 5