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. There are three selector algorithms.
91 Loop through every path in the path group, sending the same amount of IO to
95 Send the next bunch of IO down the path with the least amount of outstanding IO.
98 Choose the path for the next bunch of IO based on the amount of outstanding IO
99 to the path and its relative throughput.
102 .B path_grouping_policy
103 The default path grouping policy to apply to unspecified
104 multipaths. Possible values are
108 1 path per priority group
111 all paths in 1 priority group
114 1 priority group per serial number
117 1 priority group per priority value. Priorities are determined by
118 callout programs specified as a global, per-controller or
119 per-multipath option in the configuration file.
121 .B group_by_node_name
122 1 priority group per target node name. Target node names are fetched
123 in /sys/class/fc_transport/target*/node_name.
125 Default value is \fImultibus\fR.
129 The default program and args to callout to obtain a unique path
130 identifier. Should be specified with an absolute path. Default value
132 .I /lib/udev/scsi_id --whitelisted --device=/dev/%n
135 The default program and args to callout to obtain a path priority
136 value. The specified program will be executed and should return a
137 numeric value specifying the relative priority of this path. Higher
138 number have a higher priority. A '%n' in the command line will be expanded
139 to the device name, a '%b' will be expanded to the device number in
143 is a valid value. Currently the following path priority programs are
147 .B mpath_prio_emc /dev/%n
148 Generate the path priority for EMC arrays
150 .B mpath_prio_alua /dev/%n
151 Generate the path priority based on the SCSI-3 ALUA settings.
153 .B mpath_prio_netapp /dev/%n
154 Generate the path priority for NetApp arrays.
156 .B mpath_prio_rdac /dev/%n
157 Generate the path priority for LSI/Engenio RDAC controller.
159 .B mpath_prio_hp_sw /dev/%n
160 Generate the path priority for Compaq/HP controller in
163 .B mpath_prio_hds_modular %b
164 Generate the path priority for Hitachi HDS Modular storage arrays.
166 Default value is \fBnone\fR.
170 Specify any device-mapper features to be used. The most common of
172 .I "1 queue_if_no_path"
173 Note that this can also be set via the
178 The default method used to determine the paths' state. Possible values
183 Read the first sector of the device
188 command to the device.
191 Query the EMC Clariion specific EVPD page 0xC0 to determine the path
195 Check the path state for HP storage arrays with Active/Standby firmware.
198 Check the path state for LSI/Engenio RDAC storage controller.
201 Read the first sector with direct I/O.
203 Default value is \fIreadsector0\fR.
207 Tell the daemon to manage path group failback, or not to. 0 or
209 means immediate failback, values >0 means deferred failback (in
212 means no failback. Default value is
216 The number of IO to route to a path before switching to the next in
217 the same path group. Default is
221 If set to \fIpriorities\fR the multipath configurator will assign
222 path weights as "path prio * rr_min_io". Possible values are
230 Specify the number of retries until disable queueing, or
232 for immediate failure (no queueing),
234 for never stop queueing. Default is 0.
236 .B user_friendly_names
239 , using the bindings file
240 .I /etc/multipath/bindings
241 to assign a persistent and unique alias to the multipath, in the form of mpath<n>.
244 use the WWID as the alias. In either case this be will
245 be overriden by any specific aliases in the \fImultipaths\fR section.
250 Specify the maximum number of file descriptors that can be opened by multipath
251 and multipathd. This is equivalent to ulimit -n. A value of \fImax\fR will set
252 this to the system limit from /proc/sys/fs/nr_open. If this is not set, the
253 maximum number of open fds is taken from the calling process. It is usually
254 1024. To be safe, this should be set to the maximum number of paths plus 32,
255 if that number is greated than 1024.
258 Specify the timeout to user for path checkers that issue scsi commands with an
259 explict timeout, in seconds; default taken from
260 .I /sys/block/sd<x>/device/timeout
263 Specify the number of seconds the scsi layer will wait after a problem has been
264 detected on a FC remote port before failing IO to devices on that remote port.
265 This should be smaller than dev_loss_tmo. Setting this to
267 will disable the timeout.
270 Specify the number of seconds the scsi layer will wait after a problem has
271 been detected on a FC remote port before removing it from the system.
273 .B queue_without_daemon
276 , when multipathd stops, queueing will be turned off for all devices.
277 This is useful for devices that set no_path_retry. If a machine is
278 shut down while all paths to a device are down, it is possible to hang waiting
279 for IO to return from the device after multipathd has been stopped. Without
280 multipathd running, access to the paths cannot be restored, and the kernel
281 cannot be told to stop queueing IO. Setting queue_without_daemon to
283 , avoids this problem. Default is
286 .SH "blacklist section"
289 section is used to exclude specific device from inclusion in the
290 multipath topology. It is most commonly used to exclude local disks or
291 LUNs for the array controller.
293 The following keywords are recognized:
296 The \fIWorld Wide Identification\fR of a device.
299 Regular expression of the device nodes to be excluded.
302 Subsection for the device description. This subsection recognizes the
306 keywords. For a full description of these keywords please see the
309 .SH "blacklist_exceptions section"
311 .I blacklist_exceptions
312 section is used to revert the actions of the
314 section, ie to include specific device in the
315 multipath topology. This allows to selectively include devices which
316 would normally be excluded via the
320 The following keywords are recognized:
323 The \fIWorld Wide Identification\fR of a device.
326 Regular expression of the device nodes to be excluded.
329 Subsection for the device description. This subsection recognizes the
333 keywords. For a full description of these keywords please see the
336 .SH "multipaths section"
337 The only recognized attribute for the
345 subsection recognizes the following attributes:
348 Index of the container. Mandatory for this subsection.
351 (Optional) symbolic name for the multipath map.
353 The following attributes are optional; if not set the default values
361 .B path_grouping_policy
373 .SH "devices section"
374 The only recognized attribute for the
382 subsection recognizes the following attributes:
385 (Mandatory) Vendor identifier
388 (Mandatory) Product identifier
391 Product strings to blacklist for this vendor
394 (Optional) The hardware handler to use for this device type.
395 The following hardware handler are implemented:
399 Hardware handler for EMC storage arrays.
402 The following attributes are optional; if not set the default values
410 .B path_grouping_policy
441 processes being hung and not killable in situations where all the paths to the LUN go offline.
442 It is advisable to use the
452 was developed by Christophe Varoqui, <christophe.varoqui@opensvc.com> and others.