Provided by: multipath-tools_0.4.9-3ubuntu7.16_amd64 
NAME
multipath.conf - multipath daemon configuration file
DESCRIPTION
multipath.conf is the configuration file for the multipath daemon. It is used to overwrite
the built-in configuration table of multipathd. Any line whose first non-white-space
character is a '#' is considered a comment line. Empty lines are ignored.
SYNTAX
The configuration file contains entries of the form:
<section> {
<attribute> <value>
...
<subsection> {
<attribute> <value>
...
}
}
Each section contains one or more attributes or subsections. The recognized keywords for
attributes or subsections depend on the section in which they occor.
The following section keywords are recognized:
defaults This section defines default values for attributes which are used
whenever no specific setting is given.
blacklist This section defines which devices should be excluded from the multipath
topology discovery.
blacklist_exceptions
This section defines which devices should be included in the multipath
topology discovery, despite being listed in the blacklist section.
multipaths This section defines the multipath topologies. They are indexed by a
World Wide Identifier(wwid), which is the result of the getuid_callout
program.
devices This section defines the device-specific settings.
defaults section
The defaults section recognizes the following keywords:
polling_interval interval between two path checks in seconds For properly functioning
paths, the interval between checks will gradually increase to (4 *
polling_interval); default is 5
verbosity default verbosity. Higher values increase the verbosity level. Valid
levels are between 0 and 6; default is 2
selector The default path selector algorithm to use; they are offered by the
kernel multipath target. The only currently implemented is round-robin 0
path_grouping_policy
The default path grouping policy to apply to unspecified multipaths.
Possible values are
failover 1 path per priority group
multibus all paths in 1 priority group
group_by_serial
1 priority group per serial number
group_by_prio
1 priority group per priority value. Priorities are
determined by callout programs specified as a global, per-
controller or per-multipath option in the configuration file.
group_by_node_name
1 priority group per target node name. Target node names are
fetched in /sys/class/fc_transport/target*/node_name.
Default value is multibus.
getuid_callout The default program and args to callout to obtain a unique path
identifier. Should be specified with an absolute path. Default value is
/lib/udev/scsi_id --whitelisted --device=/dev/%n
prio_callout The default program and args to callout to obtain a path priority value.
The specified program will be executed and should return a numeric value
specifying the relative priority of this path. Higher number have a
higher priority. A '%n' in the command line will be expanded to the
device name, a '%b' will be expanded to the device number in major:minor
format. none is a valid value. Currently the following path priority
programs are implemented:
mpath_prio_emc /dev/%n
Generate the path priority for EMC arrays
mpath_prio_alua /dev/%n
Generate the path priority based on the SCSI-3 ALUA settings.
mpath_prio_netapp /dev/%n
Generate the path priority for NetApp arrays.
mpath_prio_rdac /dev/%n
Generate the path priority for LSI/Engenio RDAC controller.
mpath_prio_hp_sw /dev/%n
Generate the path priority for Compaq/HP controller in
active/standby mode.
mpath_prio_hds_modular %b
Generate the path priority for Hitachi HDS Modular storage
arrays.
Default value is none.
features Specify any device-mapper features to be used. The most common of these
features is 1 queue_if_no_path Note that this can also be set via the
no_path_retry keyword.
path_checker The default method used to determine the paths' state. Possible values
are
readsector0 Read the first sector of the device
tur Issue a TEST UNIT READY command to the device.
emc_clariion
Query the EMC Clariion specific EVPD page 0xC0 to determine
the path state.
hp_sw Check the path state for HP storage arrays with
Active/Standby firmware.
rdac Check the path state for LSI/Engenio RDAC storage controller.
directio Read the first sector with direct I/O.
Default value is readsector0.
failback Tell the daemon to manage path group failback, or not to. 0 or immediate
means immediate failback, values >0 means deferred failback (in seconds).
manual means no failback. Default value is manual
rr_min_io The number of IO to route to a path before switching to the next in the
same path group. Default is 1000
rr_weight If set to priorities the multipath configurator will assign path weights
as "path prio * rr_min_io". Possible values are priorities or uniform.
Default is uniform.
no_path_retry Specify the number of retries until disable queueing, or fail for
immediate failure (no queueing), queue for never stop queueing. Default
is 0.
user_friendly_names
If set to yes , using the bindings file /etc/multipath/bindings to assign
a persistent and unique alias to the multipath, in the form of mpath<n>.
If set to no use the WWID as the alias. In either case this be will be
overridden by any specific aliases in the multipaths section. Default is
no
wwids_file The full pathname of the wwids file, which is used by multipath to keep
track of the wwids for LUNs it has created multipath devices on in the
past. Defaults to /etc/multipath/wwids
max_fds Specify the maximum number of file descriptors that can be opened by
multipath and multipathd. This is equivalent to ulimit -n. A value of
max will set this to the system limit from /proc/sys/fs/nr_open. If this
is not set, the maximum number of open fds 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 greated than 1024.
checker_timeout Specify the timeout to user for path checkers that issue scsi commands
with an explict timeout, in seconds; default taken from
/sys/block/sd<x>/device/timeout
fast_io_fail_tmo Specify the number of seconds the scsi layer will wait after a problem
has been detected on a FC remote port before failing IO to devices on
that remote port. This should be smaller than dev_loss_tmo. Setting this
to off will disable the timeout.
dev_loss_tmo Specify the number of seconds the scsi layer will wait after a problem
has been detected on a FC remote port before removing it from the system.
queue_without_daemon
If set to no , when multipathd stops, queueing will be turned off for all
devices. This is useful for devices that set no_path_retry. If a
machine is shut down while all paths to a device are down, it is possible
to hang waiting for IO to return from the device after multipathd has
been stopped. Without multipathd running, access to the paths cannot be
restored, and the kernel cannot be told to stop queueing IO. Setting
queue_without_daemon to no , avoids this problem. Default is yes
blacklist section
The blacklist section is used to exclude specific device from inclusion in the multipath
topology. It is most commonly used to exclude local disks or LUNs for the array
controller.
The following keywords are recognized:
wwid The World Wide Identification of a device.
devnode Regular expression of the device nodes to be excluded.
device Subsection for the device description. This subsection recognizes the
vendor and product keywords. For a full description of these keywords
please see the devices section description.
blacklist_exceptions section
The blacklist_exceptions section is used to revert the actions of the blacklist section,
ie to include specific device in the multipath topology. This allows to selectively
include devices which would normally be excluded via the blacklist section.
The following keywords are recognized:
wwid The World Wide Identification of a device.
devnode Regular expression of the device nodes to be excluded.
device Subsection for the device description. This subsection recognizes the
vendor and product keywords. For a full description of these keywords
please see the devices section description.
multipaths section
The only recognized attribute for the multipaths section is the multipath subsection.
The multipath subsection recognizes the following attributes:
wwid Index of the container. Mandatory for this subsection.
alias (Optional) symbolic name for the multipath map.
The following attributes are optional; if not set the default values are taken from the
defaults section:
path_grouping_policy
path_selector
failback
no_path_retry
rr_min_io
devices section
The only recognized attribute for the devices section is the device subsection.
The device subsection recognizes the following attributes:
vendor (Mandatory) Vendor identifier
product (Mandatory) Product identifier
product_blacklist
Product strings to blacklist for this vendor
hardware_handler (Optional) The hardware handler to use for this device type. The
following hardware handler are implemented:
1 emc Hardware handler for EMC storage arrays.
The following attributes are optional; if not set the default values are taken from the
defaults section:
path_grouping_policy
getuid_callout
path_selector
path_checker
features
prio_callout
failback
rr_weight
no_path_retry
rr_min_io
fast_io_fail_tmo
dev_loss_tmo
KNOWN ISSUES
The usage of queue_if_no_path option can lead to D state processes being hung and not
killable in situations where all the paths to the LUN go offline. It is advisable to use
the no_path_retry option instead.
SEE ALSO
udev(8), dmsetup(8) multipath(8) multipathd(8)
AUTHORS
multipath was developed by Christophe Varoqui, <christophe.varoqui@opensvc.com> and
others.
30 November 2006 MULTIPATH.CONF(5)