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
73 .B max_polling_interval;
77 .B max_polling_interval
78 maximal interval between two path checks in seconds; default is
79 .I 4 * polling_interval
82 directory where udev creates its device nodes; default is
86 default verbosity. Higher values increase the verbosity level. Valid
87 levels are between 0 and 6; default is
91 The default path selector algorithm to use; they are offered by the
92 kernel multipath target. There are three selector algorithms.
96 Loop through every path in the path group, sending the same amount of IO to
100 Send the next bunch of IO down the path with the least amount of outstanding IO.
103 Choose the path for the next bunch of IO based on the amount of outstanding IO
104 to the path and its relative throughput.
107 .B path_grouping_policy
108 The default path grouping policy to apply to unspecified
109 multipaths. Possible values are
113 1 path per priority group
116 all paths in 1 priority group
119 1 priority group per serial number
122 1 priority group per priority value. Priorities are determined by
123 callout programs specified as a global, per-controller or
124 per-multipath option in the configuration file.
126 .B group_by_node_name
127 1 priority group per target node name. Target node names are fetched
128 in /sys/class/fc_transport/target*/node_name.
130 Default value is \fImultibus\fR.
134 The default program and args to callout to obtain a unique path
135 identifier. Should be specified with an absolute path. Default value
137 .I /lib/udev/scsi_id --whitelisted --device=/dev/%n
140 The default program and args to callout to obtain a path priority
141 value. The specified program will be executed and should return a
142 numeric value specifying the relative priority of this path. Higher
143 number have a higher priority. A '%n' in the command line will be expanded
144 to the device name, a '%b' will be expanded to the device number in
148 is a valid value. Currently the following path priority programs are
152 .B mpath_prio_emc /dev/%n
153 Generate the path priority for EMC arrays
155 .B mpath_prio_alua /dev/%n
156 Generate the path priority based on the SCSI-3 ALUA settings.
158 .B mpath_prio_ontap /dev/%n
159 Generate the path priority for NetApp arrays.
161 .B mpath_prio_rdac /dev/%n
162 Generate the path priority for LSI/Engenio RDAC controller.
164 .B mpath_prio_hp_sw /dev/%n
165 Generate the path priority for Compaq/HP controller in
168 .B mpath_prio_hds_modular %b
169 Generate the path priority for Hitachi HDS Modular storage arrays.
171 Default value is \fBnone\fR.
175 Specify any device-mapper features to be used. Syntax is
179 is the number of features in
181 Possible values for the feature list are
185 Queue IO if no path is active; identical to the
190 Disable automatic partitions generation via kpartx.
194 The default method used to determine the paths' state. Possible values
199 Read the first sector of the device
204 command to the device.
207 Query the EMC Clariion specific EVPD page 0xC0 to determine the path
211 Check the path state for HP storage arrays with Active/Standby firmware.
214 Check the path state for LSI/Engenio RDAC storage controller.
217 Read the first sector with direct I/O.
219 Default value is \fIreadsector0\fR.
223 Tell the daemon to manage path group failback, or not to. 0 or
225 means immediate failback, values >0 means deferred failback (in
228 means no failback. Default value is
232 The number of IO to route to a path before switching to the next in
233 the same path group. Default is
237 If set to \fIpriorities\fR the multipath configurator will assign
238 path weights as "path prio * rr_min_io". Possible values are
246 Specify the number of retries until disable queueing, or
248 for immediate failure (no queueing),
250 for never stop queueing. Default is 0.
252 .B user_friendly_names
255 , using the bindings file
256 .I /etc/multipath/bindings
257 to assign a persistent and unique alias to the multipath, in the form of mpath<n>.
260 use the WWID as the alias. In either case this be will
261 be overriden by any specific aliases in the \fImultipaths\fR section.
266 Specify the maximum number of file descriptors that can be opened by multipath
267 and multipathd. This is equivalent to ulimit -n. A value of \fImax\fR will set
268 this to the system limit from /proc/sys/fs/nr_open. If this is not set, the
269 maximum number of open fds is taken from the calling process. It is usually
270 1024. To be safe, this should be set to the maximum number of paths plus 32,
271 if that number is greated than 1024.
274 Specify the timeout to user for path checkers that issue scsi commands with an
275 explict timeout, in seconds; default taken from
276 .I /sys/block/sd<x>/device/timeout
279 Specify the number of seconds the scsi layer will wait after a problem has been
280 detected on a FC remote port before failing IO to devices on that remote port.
281 This should be smaller than dev_loss_tmo. Setting this to
283 will disable the timeout.
286 Specify the number of seconds the scsi layer will wait after a problem has
287 been detected on a FC remote port before removing it from the system.
289 .B queue_without_daemon
292 , when multipathd stops, queueing will be turned off for all devices.
293 This is useful for devices that set no_path_retry. If a machine is
294 shut down while all paths to a device are down, it is possible to hang waiting
295 for IO to return from the device after multipathd has been stopped. Without
296 multipathd running, access to the paths cannot be restored, and the kernel
297 cannot be told to stop queueing IO. Setting queue_without_daemon to
299 , avoids this problem. Default is
303 The full pathname of the binding file to be used when the user_friendly_names option is set. Defaults to
304 .I /var/lib/multipath/bindings
306 .SH "blacklist section"
309 section is used to exclude specific device from inclusion in the
310 multipath topology. It is most commonly used to exclude local disks or
311 LUNs for the array controller.
313 The following keywords are recognized:
316 The \fIWorld Wide Identification\fR of a device.
319 Regular expression of the device nodes to be excluded.
322 Subsection for the device description. This subsection recognizes the
326 keywords. For a full description of these keywords please see the
329 .SH "blacklist_exceptions section"
331 .I blacklist_exceptions
332 section is used to revert the actions of the
334 section, ie to include specific device in the
335 multipath topology. This allows to selectively include devices which
336 would normally be excluded via the
340 The following keywords are recognized:
343 The \fIWorld Wide Identification\fR of a device.
346 Regular expression of the device nodes to be excluded.
349 Subsection for the device description. This subsection recognizes the
353 keywords. For a full description of these keywords please see the
356 .SH "multipaths section"
357 The only recognized attribute for the
365 subsection recognizes the following attributes:
368 Index of the container. Mandatory for this subsection.
371 (Optional) symbolic name for the multipath map.
373 The following attributes are optional; if not set the default values
383 .B path_grouping_policy
397 .SH "devices section"
398 The only recognized attribute for the
406 subsection recognizes the following attributes:
409 (Mandatory) Vendor identifier
412 (Mandatory) Product identifier
415 (Optional) Revision identfier
418 (Optional) Product strings to blacklist for this vendor
421 (Optional) The hardware handler to use for this device type.
422 The following hardware handler are implemented:
426 Hardware handler for EMC storage arrays.
429 The following attributes are optional; if not set the default values
437 .B path_grouping_policy
468 processes being hung and not killable in situations where all the paths to the LUN go offline.
469 It is advisable to use the
479 was developed by Christophe Varoqui, <christophe.varoqui@opensvc.com> and others.