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are logged at level 3 until the device is restored. If set to always,
every path checker error is logged at logging level 2. The default
value is always.
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Chapter 4. The DM-Multipath Configuration File
fast_io_fail_tmo (Red Hat Enterprise Linux 5.7 and later) 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 (Red Hat Enterprise Linux 5.7 and later) 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. The default value is
determined by the OS.
file_tim eout (Red Hat Enterprise Linux 5.7 and later) The number of seconds
multipath will wait for a necessary file to appear while setting up a
multipath device. The default value is 90.
4.4. Multipaths Device Configuration Attributes
Table 4.2,  Multipath Attributes shows the attributes that you can set in the multipaths section of the
multipath.conf configuration file for each specific multipath device. These attributes apply only to
the one specified multipath. These defaults are used by DM-Multipath and override attributes set in the
defaults and devices sections of the multipath.conf file.
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Red Hat Enterprise Linux 5 DM Multipath
Table 4 .2. Multipath Attributes
Attribute Description
wwid Specifies the WWID of the multipath device to which the
multipath attributes apply.
alias Specifies the symbolic name for the multipath device to which the
multipath attributes apply.
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
prio_callout Specifies the default program and arguments to call out to obtain a
path weight. Weights are summed for each path group to determine
the next path group to use in case of failure. "none" is a valid value.
path_selector Specifies the default algorithm to use in determining what path to
use for the next I/O operation.
failback
Specifies path group failback.
A value of 0 or immediate specifies that as soon as there is a
path group with a higher priority than the current path group the
system switches to that path group.
A numeric value greater than zero specifies deferred failback,
expressed in seconds.
A value of m anual specifies that failback can happen only with
operator intervention.
rr_weight
If set to priorities, then instead of sending rr_min_io
requests to a path before calling 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_callout
program. Currently, there are priority callouts only for devices that
use the group_by_prio path grouping policy, which means that
all the paths in a path group will always have the same priority.
If set to uniform, all path weights are equal.
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.
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Chapter 4. The DM-Multipath Configuration File
A value of fail indicates immediate failure, without queueing.
A value of queue indicates that queueing should not stop until the
path is fixed.
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 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 with the
alias attribute for a specific multipath device.
flush_on_last_del (Red Hat Enterprise Linux 5.3 and later) If set to yes, the
multipathd daemon will disable queueing when the last path to a
device has been deleted.
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.
mode (Red Hat Enterprise Linux 5.3 and later) The mode to use for the
multipath device nodes, in octal. The default value is determined by
the process.
uid (Red Hat Enterprise Linux 5.3 and later) The user ID to use for the
multipath device nodes. You must use the numeric user ID. The
default value is determined by the process.
gid (Red Hat Enterprise Linux 5.3 and later) The group ID to use for the
multipath device nodes. You must use the numeric group ID. The
default value is determined by the process.
The following example shows multipath attributes specified in the configuration file for two specific [ Pobierz całość w formacie PDF ]