1 .TH MULTIPATH.CONF 5 "30 November 2006"
3 multipath.conf \- multipath daemon configuration file
6 is the configuration file for the multipath daemon. It is used to
7 overwrite the built-in configuration table of \fBmultipathd\fP.
8 Any line whose first non-white-space character is a '#' is considered
9 a comment line. Empty lines are ignored.
11 The configuration file contains entries of the form:
35 Each \fIsection\fP contains one or more attributes or subsections. The
36 recognized keywords for attributes or subsections depend on the
37 section in which they occor.
39 The following \fIsection\fP keywords are recognized:
42 This section defines default values for attributes which are used
43 whenever no values are given in the appropriate device or multipath
47 This section defines which devices should be excluded from the
48 multipath topology discovery.
50 .B blacklist_exceptions
51 This section defines which devices should be included in the
52 multipath topology discovery, despite being listed in the
57 This section defines the multipath topologies. They are indexed by a
58 \fIWorld Wide Identifier\fR(wwid), which is the result of the
59 \fIgetuid_callout\fR program.
62 This section defines the device-specific settings.
65 .SH "defaults section"
68 section recognizes the following keywords:
71 interval between two path checks in seconds For properly functioning paths,
72 the interval between checks will gradually increase to (4 * polling_interval);
77 directory where udev creates its device nodes; default is
81 default verbosity. Higher values increase the verbosity level. Valid
82 levels are between 0 and 6; default is
86 The default path selector algorithm to use; they are offered by the
87 kernel multipath target. The only currently implemented is
90 .B path_grouping_policy
91 The default path grouping policy to apply to unspecified
92 multipaths. Possible values are
96 1 path per priority group
99 all paths in 1 priority group
102 1 priority group per serial number
105 1 priority group per priority value. Priorities are determined by
106 callout programs specified as a global, per-controller or
107 per-multipath option in the configuration file.
109 .B group_by_node_name
110 1 priority group per target node name. Target node names are fetched
111 in /sys/class/fc_transport/target*/node_name.
113 Default value is \fImultibus\fR.
117 The default program and args to callout to obtain a unique path
118 identifier. Should be specified with an absolute path. Default value
120 .I /lib/udev/scsi_id --whitelisted --device=/dev/%n
123 The default program and args to callout to obtain a path priority
124 value. The specified program will be executed and should return a
125 numeric value specifying the relative priority of this path. Higher
126 number have a higher priority. A '%n' in the command line will be expanded
127 to the device name, a '%b' will be expanded to the device number in
131 is a valid value. Currently the following path priority programs are
135 .B mpath_prio_emc /dev/%n
136 Generate the path priority for EMC arrays
138 .B mpath_prio_alua /dev/%n
139 Generate the path priority based on the SCSI-3 ALUA settings.
141 .B mpath_prio_netapp /dev/%n
142 Generate the path priority for NetApp arrays.
144 .B mpath_prio_rdac /dev/%n
145 Generate the path priority for LSI/Engenio RDAC controller.
147 .B mpath_prio_hp_sw /dev/%n
148 Generate the path priority for Compaq/HP controller in
151 .B mpath_prio_hds_modular %b
152 Generate the path priority for Hitachi HDS Modular storage arrays.
154 Default value is \fBnone\fR.
158 Specify any device-mapper features to be used. The most common of
160 .I "1 queue_if_no_path"
161 Note that this can also be set via the
166 The default method used to determine the paths' state. Possible values
171 Read the first sector of the device
176 command to the device.
179 Query the EMC Clariion specific EVPD page 0xC0 to determine the path
183 Check the path state for HP storage arrays with Active/Standby firmware.
186 Check the path state for LSI/Engenio RDAC storage controller.
189 Read the first sector with direct I/O.
191 Default value is \fIreadsector0\fR.
195 Tell the daemon to manage path group failback, or not to. 0 or
197 means immediate failback, values >0 means deferred failback (in
200 means no failback. Default value is
204 The number of IO to route to a path before switching to the next in
205 the same path group. Default is
209 If set to \fIpriorities\fR the multipath configurator will assign
210 path weights as "path prio * rr_min_io". Possible values are
218 Specify the number of retries until disable queueing, or
220 for immediate failure (no queueing),
222 for never stop queueing. Default is 0.
224 .B user_friendly_names
227 , using the bindings file
228 .I /etc/multipath/bindings
229 to assign a persistent and unique alias to the multipath, in the form of mpath<n>.
232 use the WWID as the alias. In either case this be will
233 be overriden by any specific aliases in the \fImultipaths\fR section.
238 Specify the maximum number of file descriptors that can be opened by multipath
239 and multipathd. This is equivalent to ulimit -n. A value of \fImax\fR will set
240 this to the system limit from /proc/sys/fs/nr_open. If this is not set, the
241 maximum number of open fds is taken from the calling process. It is usually
242 1024. To be safe, this should be set to the maximum number of paths plus 32,
243 if that number is greated than 1024.
246 Specify the number of seconds the scsi layer will wait after a problem has been
247 detected on a FC remote port before failing IO to devices on that remote port.
248 This should be smaller than dev_loss_tmo. Setting this to
250 will disable the timeout.
253 Specify the number of seconds the scsi layer will wait after a problem has
254 been detected on a FC remote port before removing it from the system.
256 .B queue_without_daemon
259 , when multipathd stops, queueing will be turned off for all devices.
260 This is useful for devices that set no_path_retry. If a machine is
261 shut down while all paths to a device are down, it is possible to hang waiting
262 for IO to return from the device after multipathd has been stopped. Without
263 multipathd running, access to the paths cannot be restored, and the kernel
264 cannot be told to stop queueing IO. Setting queue_without_daemon to
266 , avoids this problem. Default is
269 .SH "blacklist section"
272 section is used to exclude specific device from inclusion in the
273 multipath topology. It is most commonly used to exclude local disks or
274 LUNs for the array controller.
276 The following keywords are recognized:
279 The \fIWorld Wide Identification\fR of a device.
282 Regular expression of the device nodes to be excluded.
285 Subsection for the device description. This subsection recognizes the
289 keywords. For a full description of these keywords please see the
292 .SH "blacklist_exceptions section"
294 .I blacklist_exceptions
295 section is used to revert the actions of the
297 section, ie to include specific device in the
298 multipath topology. This allows to selectively include devices which
299 would normally be excluded via the
303 The following keywords are recognized:
306 The \fIWorld Wide Identification\fR of a device.
309 Regular expression of the device nodes to be excluded.
312 Subsection for the device description. This subsection recognizes the
316 keywords. For a full description of these keywords please see the
319 .SH "multipaths section"
320 The only recognized attribute for the
328 subsection recognizes the following attributes:
331 Index of the container. Mandatory for this subsection.
334 (Optional) symbolic name for the multipath map.
336 The following attributes are optional; if not set the default values
344 .B path_grouping_policy
356 .SH "devices section"
357 The only recognized attribute for the
365 subsection recognizes the following attributes:
368 (Mandatory) Vendor identifier
371 (Mandatory) Product identifier
374 Product strings to blacklist for this vendor
377 (Optional) The hardware handler to use for this device type.
378 The following hardware handler are implemented:
382 Hardware handler for EMC storage arrays.
385 The following attributes are optional; if not set the default values
393 .B path_grouping_policy
424 processes being hung and not killable in situations where all the paths to the LUN go offline.
425 It is advisable to use the
435 was developed by Christophe Varoqui, <christophe.varoqui@opensvc.com> and others.