.TH MULTIPATH.CONF 5 "30 November 2006" .SH NAME multipath.conf \- multipath daemon configuration file .SH DESCRIPTION .B "multipath.conf" is the configuration file for the multipath daemon. It is used to overwrite the built-in configuration table of \fBmultipathd\fP. Any line whose first non-white-space character is a '#' is considered a comment line. Empty lines are ignored. .SH SYNTAX The configuration file contains entries of the form: .RS .nf .ft B .sp
{ .RS .ft B .I "..." .ft B { .RS .ft B .I "..." .RE } .RE } .ft R .fi .RE .LP Each \fIsection\fP contains one or more attributes or subsections. The recognized keywords for attributes or subsections depend on the section in which they occor. .LP The following \fIsection\fP keywords are recognized: .TP 17 .B defaults This section defines default values for attributes which are used whenever no specific setting is given. .TP .B blacklist This section defines which devices should be excluded from the multipath topology discovery. .TP .B blacklist_exceptions This section defines which devices should be included in the multipath topology discovery, despite being listed in the .I blacklist section. .TP .B multipaths This section defines the multipath topologies. They are indexed by a \fIWorld Wide Identifier\fR(wwid), which is the result of the \fIgetuid_callout\fR program. .TP .B devices This section defines the device-specific settings. .RE .LP .SH "defaults section" The .B defaults section recognizes the following keywords: .TP 17 .B polling_interval interval between two path checks in seconds; default is .I 5 .TP .B udev_dir directory where udev creates its device nodes; default is .I /dev .TP .B selector The default path selector algorithm to use; they are offered by the kernel multipath target. The only currently implemented is .I "round-robin 0" .TP .B path_grouping_policy The default path grouping policy to apply to unspecified multipaths. Possible values are .RS .TP 12 .B failover 1 path per priority group .TP .B multibus all paths in 1 priority group .TP .B group_by_serial 1 priority group per serial number .TP .B 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. .TP .B group_by_node_name 1 priority group per target node name. Target node names are fetched in /sys/class/fc_transport/target*/node_name. .TP Default value is \fImultibus\fR. .RE .TP .B 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 .I /lib/udev/scsi_id -g -u -d /dev/%n .TP .B 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 .I major:minor format. .I "none" is a valid value. Currently the following path priority programs are implemented: .RS .TP 12 .B mpath_prio_emc /dev/%n Generate the path priority for EMC arrays .TP .B mpath_prio_alua /dev/%n Generate the path priority based on the SCSI-3 ALUA settings. .TP .B mpath_prio_netapp /dev/%n Generate the path priority for NetApp arrays. .TP .B mpath_prio_rdac /dev/%n Generate the path priority for LSI/Engenio RDAC controller. .TP .B mpath_prio_hp_sw /dev/%n Generate the path priority for Compaq/HP controller in active/standby mode. .TP .B mpath_prio_hds_modular %b Generate the path priority for Hitachi HDS Modular storage arrays. .TP Default value is \fBnone\fR. .RE .TP .B features Specify any device-mapper features to be used. The most common of these features is .I "1 queue_if_no_path" Note that this can also be set via the .I no_path_retry keyword. .TP .B path_checker The default method used to determine the paths' state. Possible values are .RS .TP 12 .B readsector0 Read the first sector of the device .TP .B tur Issue a .I TEST UNIT READY command to the device. .TP .B emc_clariion Query the EMC Clariion specific EVPD page 0xC0 to determine the path state. .TP .B hp_sw Check the path state for HP storage arrays with Active/Standby firmware. .TP .B rdac Check the path state for LSI/Engenio RDAC storage controller. .TP .B directio Read the first sector with direct I/O. .TP Default value is \fIreadsector0\fR. .RE .TP .B failback Tell the daemon to manage path group failback, or not to. 0 or .I immediate means immediate failback, values >0 means deferred failback (in seconds). .I manual means no failback. Default value is .I manual .TP .B rr_min_io The number of IO to route to a path before switching to the next in the same path group. Default is .I 1000 .TP .B rr_weight If set to \fIpriorities\fR the multipath configurator will assign path weights as "path prio * rr_min_io". Possible values are .I priorities or .I uniform . Default is .I uniform .TP .B no_path_retry Specify the number of retries until disable queueing, or .I fail for immediate failure (no queueing), .I queue for never stop queueing. Default is 0. .TP .B user_friendly_names If set to .I yes , using the bindings file .I /var/lib/multipath/bindings to assign a persistent and unique alias to the multipath, in the form of mpath. If set to .I no use the WWID as the alias. In either case this be will be overriden by any specific aliases in the \fImultipaths\fR section. Default is .I no . .SH "blacklist section" The .I 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. .LP The following keywords are recognized: .TP 17 .B wwid The \fIWorld Wide Identification\fR of a device. .TP .B devnode Regular expression of the device nodes to be excluded. .TP .B device Subsection for the device description. This subsection recognizes the .I vendor and .I product keywords. For a full description of these keywords please see the .I devices section description. .SH "blacklist_exceptions section" The .I blacklist_exceptions section is used to revert the actions of the .I blacklist section, ie to include specific device in the multipath topology. This allows to selectively include devices which would normally be excluded via the .I blacklist section. .LP The following keywords are recognized: .TP 17 .B wwid The \fIWorld Wide Identification\fR of a device. .TP .B devnode Regular expression of the device nodes to be excluded. .TP .B device Subsection for the device description. This subsection recognizes the .I vendor and .I product keywords. For a full description of these keywords please see the .I devices section description. .SH "multipaths section" The only recognized attribute for the .B multipaths section is the .I multipath subsection. .LP The .B multipath subsection recognizes the following attributes: .TP 17 .B wwid Index of the container. Mandatory for this subsection. .TP .B alias (Optional) symbolic name for the multipath map. .LP The following attributes are optional; if not set the default values are taken from the .I defaults section: .sp 1 .PD .1v .RS .TP 18 .B path_grouping_policy .TP .B path_selector .TP .B failback .TP .B no_path_retry .TP .B rr_min_io .RE .PD .LP .SH "devices section" The only recognized attribute for the .B devices section is the .I device subsection. .LP The .I device subsection recognizes the following attributes: .TP 17 .B vendor (Mandatory) Vendor identifier .TP .B product (Mandatory) Product identifier .TP .B product_blacklist Product strings to blacklist for this vendor .TP .B hardware_handler (Optional) The hardware handler to use for this device type. The following hardware handler are implemented: .RS .TP 12 .B 1 emc Hardware handler for EMC storage arrays. .RE .LP The following attributes are optional; if not set the default values are taken from the .I defaults section: .sp 1 .PD .1v .RS .TP 18 .B path_grouping_policy .TP .B getuid_callout .TP .B path_selector .TP .B path_checker .TP .B features .TP .B prio_callout .TP .B failback .TP .B rr_weight .TP .B no_path_retry .TP .B rr_min_io .RE .PD .LP .SH "KNOWN ISSUES" The usage of .B queue_if_no_path option can lead to .B 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 .B no_path_retry option instead. .SH "SEE ALSO" .BR udev (8), .BR dmsetup (8) .BR multipath (8) .BR multipathd (8) .SH AUTHORS .B multipath was developed by Christophe Varoqui, and others.