Configuration File Defaults
15
defaults {
user_friendly_names yes
path_grouping_policy multibus
}
Table 4.1, “Multipath Configuration Defaults”
describes the attributes that are set in the
defaults
section of the
multipath.conf
configuration file. These values are used by DM-Multipath unless
they are overwritten by the attributes specified in the
devices
and
multipaths
sections of the
multipath.conf
file.
Attribute
Description
udev_dir
Specifies the directory where
udev
device nodes are created. The
default value is
/udev
.
polling_interval
Specifies the interval between two path checks in seconds. The
default value is 5.
selector
Specifies the default algorithm to use in determining what path to
use for the next I/O operation. The default value is
round-robin
0
.
path_grouping_policy
Specifies the default path grouping policy to apply to unspecified
multipaths. Possible values include:
failover
= 1 path per priority group
multibus
= all valid paths in 1 priority group
group_by_serial
= 1 priority group per detected serial number
group_by_prio
= 1 priority group per path priority value
group_by_node_name
= 1 priority group per target node name
The default value is
failover
.
getuid_callout
Specifies the default program and arguments to call out to obtain a
unique path identifier. An absolute path is required.
The default value is
/sbin/scsi_id -g -u -s
.
prio_callout
Specifies the the default program and arguments to call out to
obtain a path priority value. For example, the ALUA bits in SPC-3
provide an exploitable prio value for example. "none" is a valid
value. The default value is no callout, indicating all paths are equal
path_checker
Specifies the default method used to determine the state
of the paths. Possible values include:
readsector0
,
tur
,
emc_clariion
,
hp_sw
, and
directio
. The default value is
readsector0
.
rr_min_io
Specifies the number of I/O requests to route to a path before
switching to the next path in the current path group. The default
value is 1000.
max_fds
(RHEL 5.2 and later) Sets the maximum number of open file
descriptors for the
multipathd
process. In RHEL 5.3, this
option allows a value of
max
, which sets the number of open file
descriptors to the system maximum.
rr_weight
If set to
priorities
, then instead of sending
rr_min_io
requests to a path before calling
selector
to choose the