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 directory where the dynamic shared objects are stored; default is system
91 default verbosity. Higher values increase the verbosity level. Valid
92 levels are between 0 and 6; default is
96 enable reassigning of device-mapper maps. With this option multipathd
97 will remap existing device-mapper maps to always point to multipath
98 device, not the underlying block devices. Possible values are
99 \fIyes\fR and \fIno\fR. Default is
103 The default path selector algorithm to use; they are offered by the
104 kernel multipath target. There are three selector algorithms.
108 Loop through every path in the path group, sending the same amount of IO to
112 Send the next bunch of IO down the path with the least amount of outstanding IO.
115 Choose the path for the next bunch of IO based on the amount of outstanding IO
116 to the path and its relative throughput.
119 .B path_grouping_policy
120 The default path grouping policy to apply to unspecified
121 multipaths. Possible values are
125 1 path per priority group
128 all paths in 1 priority group
131 1 priority group per serial number
134 1 priority group per priority value. Priorities are determined by
135 callout programs specified as a global, per-controller or
136 per-multipath option in the configuration file.
138 .B group_by_node_name
139 1 priority group per target node name. Target node names are fetched
140 in /sys/class/fc_transport/target*/node_name.
142 Default value is \fImultibus\fR.
146 The default program and args to callout to obtain a unique path
147 identifier. Should be specified with an absolute path. Default value
149 .I /lib/udev/scsi_id --whitelisted --replace-whitespace --device=/dev/%n
152 The name of the path priority routine. The specified routine
153 should return a numeric value specifying the relative priority
154 of this path. Higher number have a higher priority.
156 is a valid value. Currently the following path priority routines
161 Return a constant priority of \fI1\fR.
164 Generate the path priority for EMC arrays.
167 Generate the path priority based on the SCSI-3 ALUA settings.
170 Generate the path priority for NetApp arrays.
173 Generate the path priority for LSI/Engenio/NetApp E-Series RDAC controller.
176 Generate the path priority for Compaq/HP controller in
180 Generate the path priority for Hitachi HDS Modular storage arrays.
183 Generate a random priority between 1 and 10.
186 Generate the path priority based on the regular expression and the
187 priority provided as argument. requires prio_args keyword.
189 Default value is \fBnone\fR.
193 Arguments to pass to to the prio function. Currently only used with
194 .I weighted, which needs a value of the form
195 .I "<hbtl|devname> <regex1> <prio1> <regex2> <prio2> ..."
197 regex can be of SCSI H:B:T:L format Ex: 1:0:.:. , *:0:0:.
199 regex can be of device name format Ex: sda , sd.e
202 Specify any device-mapper features to be used. Syntax is
206 is the number of features in
208 Possible values for the feature list are
212 Queue IO if no path is active; identical to the
217 Disable automatic partitions generation via kpartx.
221 The default method used to determine the paths state. Possible values
226 (Deprecated) Read the first sector of the device. This checker is being
227 deprecated, please use \fIdirectio\fR instead
232 command to the device.
235 Query the EMC Clariion specific EVPD page 0xC0 to determine the path
239 Check the path state for HP storage arrays with Active/Standby firmware.
242 Check the path state for LSI/Engenio/NetApp E-Series RDAC storage controller.
245 Read the first sector with direct I/O.
247 Default value is \fIdirectio\fR.
251 Tell multipathd how to manage path group failback.
255 Immediately failback to the highest priority pathgroup that contains
259 Do not perform automatic failback.
262 deferred failback (time to defer in seconds)
264 Default value is \fImanual\fR.
268 The number of IO to route to a path before switching to the next in
269 the same path group. This is only for BIO based multipath. Default is
273 The number of IO requests to route to a path before switching to the
274 next in the same path group. This is only for request based multipath.
279 If set to \fIpriorities\fR the multipath configurator will assign
280 path weights as "path prio * rr_min_io". Possible values are
288 Specify the number of retries until disable queueing, or
290 for immediate failure (no queueing),
292 for never stop queueing. Default is 0.
294 .B user_friendly_names
297 , using the bindings file
298 .I /etc/multipath/bindings
299 to assign a persistent and unique alias to the multipath, in the form of mpath<n>.
302 use the WWID as the alias. In either case this be will
303 be overriden by any specific aliases in the \fImultipaths\fR section.
310 , multipathd will disable queueing when the last path to a device has been
315 Specify the maximum number of file descriptors that can be opened by multipath
316 and multipathd. This is equivalent to ulimit -n. A value of \fImax\fR will set
317 this to the system limit from /proc/sys/fs/nr_open. If this is not set, the
318 maximum number of open fds is taken from the calling process. It is usually
319 1024. To be safe, this should be set to the maximum number of paths plus 32,
320 if that number is greated than 1024.
323 Specify the timeout to user for path checkers that issue scsi commands with an
324 explict timeout, in seconds; default taken from
325 .I /sys/block/sd<x>/device/timeout
328 Specify the number of seconds the scsi layer will wait after a problem has been
329 detected on a FC remote port before failing IO to devices on that remote port.
330 This should be smaller than dev_loss_tmo. Setting this to
332 will disable the timeout.
335 Specify the number of seconds the scsi layer will wait after a problem has
336 been detected on a FC remote port before removing it from the system.
338 .B queue_without_daemon
341 , when multipathd stops, queueing will be turned off for all devices.
342 This is useful for devices that set no_path_retry. If a machine is
343 shut down while all paths to a device are down, it is possible to hang waiting
344 for IO to return from the device after multipathd has been stopped. Without
345 multipathd running, access to the paths cannot be restored, and the kernel
346 cannot be told to stop queueing IO. Setting queue_without_daemon to
348 , avoids this problem. Default is
352 The full pathname of the binding file to be used when the user_friendly_names option is set. Defaults to
353 .I /var/lib/multipath/bindings
358 , multipathd logs the first path checker error at logging level 2. Any later
359 errors are logged at level 3 until the device is restored. If set to
361 , multipathd always logs the path checker error at logging level 2. Default is
364 .SH "blacklist section"
367 section is used to exclude specific device from inclusion in the
368 multipath topology. It is most commonly used to exclude local disks or
369 LUNs for the array controller.
371 The following keywords are recognized:
374 The \fIWorld Wide Identification\fR of a device.
377 Regular expression of the device nodes to be excluded.
380 Subsection for the device description. This subsection recognizes the
384 keywords. For a full description of these keywords please see the
387 .SH "blacklist_exceptions section"
389 .I blacklist_exceptions
390 section is used to revert the actions of the
392 section, ie to include specific device in the
393 multipath topology. This allows to selectively include devices which
394 would normally be excluded via the
398 The following keywords are recognized:
401 The \fIWorld Wide Identification\fR of a device.
404 Regular expression of the device nodes to be excluded.
407 Subsection for the device description. This subsection recognizes the
411 keywords. For a full description of these keywords please see the
414 .SH "multipaths section"
415 The only recognized attribute for the
423 subsection recognizes the following attributes:
426 Index of the container. Mandatory for this subsection.
429 (Optional) symbolic name for the multipath map.
431 The following attributes are optional; if not set the default values
441 .B path_grouping_policy
465 .SH "devices section"
466 The only recognized attribute for the
474 subsection recognizes the following attributes:
477 (Mandatory) Vendor identifier
480 (Mandatory) Product identifier
483 (Optional) Revision identfier
486 (Optional) Product strings to blacklist for this vendor
489 (Optional) The user_friendly_names prefix to use for this
490 device type, instead of the default "mpath"
493 (Optional) The hardware handler to use for this device type.
494 The following hardware handler are implemented:
498 Hardware handler for EMC storage arrays.
501 Hardware handler for LSI/Engenio/NetApp E-Series RDAC storage controller.
504 Hardware handler for Compaq/HP storage arrays in active/standby
508 Hardware handler for SCSI-3 ALUA compatible arrays.
511 The following attributes are optional; if not set the default values
519 .B path_grouping_policy
556 processes being hung and not killable in situations where all the paths to the LUN go offline.
557 It is advisable to use the
565 might lead to a deadlock if the
567 setting results in a device being removed while I/O is still queued.
568 The multipath daemon will update the
570 setting accordingly to avoid this deadlock. Hence if both values are
571 specified the order of precedence is
572 .I no_path_retry, queue_if_no_path, dev_loss_tmo
581 was developed by Christophe Varoqui, <christophe.varoqui@opensvc.com> and others.