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Specifies the default method used to determine the state of the
paths. Possible values include:
readsector0: Read the first sector of the device.
tur: Issue a TEST UNIT READY to the device.
emc_clariion: Query the EMC Clariion specific EVPD page
0xC0 to determine the path.
hp_sw: Check the path state for HP storage arrays with
Active/Standby firmware.
rdac: Check the path stat for LSI/Engenio RDAC storage controller.
directio: Read the first sector with direct I/O.
The default value is directio.
failback
Manages path group failback.
A value of immediate specifies immediate failback to the highest
priority path group that contains active paths.
A value of m anual specifies that there should not be immediate
failback but that failback can happen only with operator intervention.
A value of followover specifies that automatic failback should be
performed when the first path of a path group becomes active. This
keeps a node from automatically failing back when another node
requested the failover.
A numeric value greater than zero specifies deferred failback,
expressed in seconds.
The default value is manual.
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. This setting is
only for systems running kernels older than 2.6.31. Newer systems
should use rr_min_io_rq. The default value is 1000.
rr_min_io_rq Specifies the number of I/O requests to route to a path before
switching to the next path in the current path group, using request-
based device-mapper-multipath. This setting should be used on
systems running current kernels. On systems running kernels older
than 2.6.31, use rr_min_io. The default value is 1.
rr_weight If set to priorities, then instead of sending rr_min_io
requests to a path before calling path_selector to choose the
next path, the number of requests to send is determined by
rr_min_io times the path's priority, as determined by the prio
function. If set to uniform, all path weights are equal. The default
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Red Hat Enterprise Linux 6 DM Multipath
value is uniform.
no_path_retry
A numeric value for this attribute specifies the number of times the
system should attempt to use a failed path before disabling
queueing.
A value of fail indicates immediate failure, without queueing.
A value of queue indicates that queueing should not stop until the
path is fixed.
The default value is 0.
user_friendly_names If set to yes, specifies that the system should use the
/etc/multipath/bindings file to assign a persistent and
unique alias to the multipath, in the form of mpathn. If set to no,
specifies that the system should use the WWID as the alias for the
multipath. In either case, what is specified here will be overridden by
any device-specific aliases you specify in the multipaths section
of the configuration file. The default value is no.
queue_without_daemon If set to no, the multipathd daemon will disable queueing for all
devices when it is shut down. The default value is no.
flush_on_last_del If set to yes, the multipathd daemon will disable queueing when
the last path to a device has been deleted. The default value is no.
max_fds Sets the maximum number of open file descriptors that can be
opened by multipath and the multipathd daemon. This is
equivalent to the ulimit -n command. As of the Red Hat
Enterprise Linux 6.3 release, the default value is m ax, which sets
this to the system limit from /proc/sys/fs/nr_open. For earlier
releases, if this is not set the maximum number of open file
descriptors is taken from the calling process; it is usually 1024. To
be safe, this should be set to the maximum number of paths plus
32, if that number is greater than 1024.
checker_tim eout The timeout to use for path checkers that issue SCSI commands
with an explicit timeout, in seconds. The default value is taken from
sys/block/sdx/device/timeout.
fast_io_fail_tmo The number of seconds the SCSI layer will wait after a problem has
been detected on an FC remote port before failing I/O to devices on
that remote port. This value should be smaller than the value of
dev_loss_tmo. Setting this to off will disable the timeout. The
default value is determined by the OS.
dev_loss_tmo The number of seconds the SCSI layer will wait after a problem has
been detected on an FC remote port before removing it from the
system. Setting this to infinity will set this to 2147483647 seconds,
or 68 years. The default value is determined by the OS.
hwtable_regex_match
(Red Hat Enterprise Linux Release 6.3 and later) Controls how
multipath integrates the device configurations from the devices
section of the configuration file with the built-in device
configurations.
Each device configuration in the devices section of the
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Chapter 4. The DM-Multipath Configuration File
multipath.conf file will either create its own device
configuration or it will modify one of the built-in device
configurations. Prior to Red Hat Enterprise Linux 6.3, if the vendor,
product, and revision strings in a user's device configuration
exactly matched those strings in a built-in device configuration, the
built-in configuration was modified by the options in the user's
configuration. Otherwise. the user's device configuration was
treated as a new configuration.
If hwtable_regex_match is set to yes, a regular expression
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