-.TH MULTIPATH.CONF 5 2016-07-08 "Linux"
+.\" ----------------------------------------------------------------------------
+.\" Update the date below if you make any significant change.
+.\" Make sure there are no errors with:
+.\" groff -z -wall -b -e -t multipath/multipath.conf.5
+.\" man --warnings -E UTF-8 -l -Tutf8 -Z multipath/multipath.conf.5 >/dev/null
+.\"
+.\" TODO: Look for XXX and ???
+.\"
+.\" ----------------------------------------------------------------------------
+.
+.TH MULTIPATH.CONF 5 2017-08-18 Linux
+.
+.
+.\" ----------------------------------------------------------------------------
.SH NAME
+.\" ----------------------------------------------------------------------------
+.
multipath.conf \- multipath daemon configuration file.
+.
+.
+.\" ----------------------------------------------------------------------------
.SH DESCRIPTION
+.\" ----------------------------------------------------------------------------
+.
.B "/etc/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.
+.PP
+Currently used multipathd configuration can be displayed with the \fBmultipath -t\fR
+or \fBmultipathd show config\fR command.
+.
+.
+.\" ----------------------------------------------------------------------------
.SH SYNTAX
+.\" ----------------------------------------------------------------------------
+.
The configuration file contains entries of the form:
.RS
.nf
recognized keywords for attributes or subsections depend on the
section in which they occur.
.LP
+.
+\fB<attribute>\fR and \fB<value>\fR must be on a single line.
+\fB<attribute>\fR is one of the keywords listed in this man page.
+\fB<value>\fR is either a simple word (containing no whitespace and none of the
+characters '\(dq', '#', and '!') or \fIone\fR string enclosed in double
+quotes ("..."). Outside a quoted string, text starting with '#', and '!' is
+regarded as a comment and ignored until the end of the line. Inside a quoted
+string, '#' and '!' are normal characters, and whitespace is preserved.
+To represent a double quote character inside a double quoted string, use two
+consecutive double quotes ('""'). Thus '2.5\(dq SSD' can be written as "2.5"" SSD".
+.LP
+.
+Opening braces ('{') must follow the (sub)section name on the same line. Closing
+braces ('}') that mark the end of a (sub)section must be the only non-whitespace
+character on the line. Whitespace is ignored except inside double quotes, thus
+the indentation shown in the above example is helpful for human readers but
+not mandatory.
+.LP
+.
The following \fIsection\fP keywords are recognized:
.TP 17
.B defaults
.B blacklist_exceptions
This section defines which devices should be included in the
multipath topology discovery, despite being listed in the
-.I blacklist
-section.
+\fIblacklist\fR section.
.TP
.B multipaths
This section defines the multipath topologies. They are indexed by a
device-specific settings for all devices.
.RE
.LP
+.
+.
+.\" ----------------------------------------------------------------------------
.SH "defaults section"
-The
-.I defaults
-section recognizes the following keywords:
+.\" ----------------------------------------------------------------------------
+.
+The \fIdefaults\fR section recognizes the following keywords:
+.
+.
.TP 17
.B verbosity
Default verbosity. Higher values increase the verbosity level. Valid
levels are between 0 and 6.
.RS
.TP
-Default value is: \fB2\fR
+The default is: \fB2\fR
.RE
+.
+.
.TP
.B polling_interval
Interval between two path checks in seconds. For properly functioning paths,
-the interval between checks will gradually increase to
-.I max_polling_interval.
-This value will be overridden by the
-.I WatchdogSec
+the interval between checks will gradually increase to \fImax_polling_interval\fR.
+This value will be overridden by the \fIWatchdogSec\fR
setting in the multipathd.service definition if systemd is used.
.RS
.TP
-Default value is: \fB5\fR
+The default is: \fB5\fR
.RE
+.
+.
.TP
.B max_polling_interval
Maximal interval between two path checks in seconds.
.RS
.TP
-Default value is: \fB4 * polling_interval\fR
+The default is: \fB4 * polling_interval\fR
.RE
+.
+.
.TP
.B reassign_maps
Enable reassigning of device-mapper maps. With this option multipathd
\fIyes\fR and \fIno\fR.
.RS
.TP
-Default value is: \fBno\fR
+The default is: \fBno\fR
.RE
+.
+.
.TP
.B multipath_dir
-Directory where the dynamic shared objects are stored.
+Directory where the dynamic shared objects are stored. Defined at compile time,
+commonly \fI/lib64/multipath/\fR or \fI/lib/multipath/\fR.
.RS
.TP
-Default value is: \fB<system dependent>\fR, commonly \fI/lib64/multipath/\fR
+The default is: \fB<system dependent>\fR
.RE
+.
+.
.TP
.B path_selector
The default path selector algorithm to use; they are offered by the
.RS
.TP 12
.I "round-robin 0"
-Loop through every path in the path group, sending the same amount of IO to
-each.
+Loop through every path in the path group, sending the same amount of I/O to
+each. Some aspects of behavior can be controlled with the attributes:
+\fIrr_min_io\fR, \fIrr_min_io_rq\fR and \fIrr_weight\fR.
.TP
.I "queue-length 0"
-Send the next bunch of IO down the path with the least amount of outstanding IO.
+(Since 2.6.31 kernel) Choose the path for the next bunch of I/O based on the amount
+of outstanding I/O to the path.
.TP
.I "service-time 0"
-Choose the path for the next bunch of IO based on the amount of outstanding IO
-to the path and its relative throughput.
+(Since 2.6.31 kernel) Choose the path for the next bunch of I/O based on the amount
+of outstanding I/O to the path and its relative throughput.
.TP
-Default value is: \fBservice-time 0\fR
+The default is: \fBservice-time 0\fR
.RE
+.
+.
.TP
.B path_grouping_policy
The default path grouping policy to apply to unspecified
One priority group per target node name. Target node names are fetched
in \fI/sys/class/fc_transport/target*/node_name\fR.
.TP
-Default value is: \fBgroup_by_prio\fR
+The default is: \fBfailover\fR
+.RE
+.
+.
+.TP
+.B uid_attrs
+The udev attribute providing a unique path identifier for corresponding
+type of path devices. If this field is configured and matched with type
+of device, it would override any other methods providing for device
+unique identifier in config file, and it would activate merging uevents
+according to the identifier to promote effiecncy in processing uevents.
+It has no default value, if you want to identify path by udev attribute
+and to activate merging uevents for SCSI and DASD devices, you can set
+its value as: \fIuid_attrs "sd:ID_SERIAL dasd:ID_UID"\fR.
+.RS
+.TP
+The default is: \fB<unset>\fR
.RE
+.
+.
.TP
.B uid_attribute
The udev attribute providing a unique path identifier.
.RS
.TP
-Default value is: \fBID_SERIAL\fR for SCSI devices
+The default is: for SCSI devices \fBID_SERIAL\fR
+.TP
+The default is: for DASD devices \fBID_UID\fR
.TP
-Default value is: \fBID_UID\fR for DASD devices
+The default is: for NVME devices \fBID_WWN\fR
.RE
+.
+.
.TP
.B getuid_callout
-(Deprecated) The default program and args to callout to obtain a unique path
-identifier. Should be specified with an absolute path.
+(Superseded by \fIuid_attribute\fR) The default program and args to callout
+to obtain a unique path identifier. Should be specified with an absolute path.
+.RS
+.TP
+The default is: \fB<unset>\fR
+.RE
+.
+.
.TP
.B prio
The name of the path priority routine. The specified routine
should return a numeric value specifying the relative priority
of this path. Higher number have a higher priority.
-.I "none"
-is a valid value. Currently the following path priority routines
+\fI"none"\fR is a valid value. Currently the following path priority routines
are implemented:
.RS
.TP 12
.I sysfs
Use the sysfs attributes \fIaccess_state\fR and \fIpreferred_path\fR to
generate the path priority. This prioritizer accepts the optional prio_arg
-.I exclusive_pref_bit
+\fIexclusive_pref_bit\fR.
.TP
.I emc
(Hardware-dependent)
Generate the path priority for DGC class arrays as CLARiiON CX/AX and
-EMC VNX families.
+EMC VNX and Unity families.
.TP
.I alua
(Hardware-dependent)
.TP
.I rdac
(Hardware-dependent)
-Generate the path priority for LSI/Engenio/NetApp RDAC class as NetApp E/EF
-Series, and OEM arrays from IBM DELL SGI STK and SUN.
+Generate the path priority for LSI/Engenio/NetApp RDAC class as NetApp SANtricity
+E/EF Series, and OEM arrays from IBM DELL SGI STK and SUN.
.TP
.I hp_sw
(Hardware-dependent)
.TP
.I hds
(Hardware-dependent)
-Generate the path priority for Hitachi HDS Modular storage arrays.
+Generate the path priority for Hitachi AMS 2000 and HUS 100 families of arrays.
.TP
.I random
Generate a random priority between 1 and 10.
-.TP 12
+.TP
.I weightedpath
Generate the path priority based on the regular expression and the
priority provided as argument. Requires prio_args keyword.
.TP
+.I path_latency
+Generate the path priority based on a latency algorithm.
+Requires prio_args keyword.
+.TP
.I datacore
-???. Requires prio_args keyword.
+(Hardware-dependent)
+Generate the path priority for some DataCore storage arrays. Requires prio_args
+keyword.
.TP
.I iet
-???. Requires prio_args keyword.
-.TP
-Default value is: \fBconst\fR
+(iSCSI only)
+Generate path priority for iSCSI targets based on IP address. Requires
+prio_args keyword.
+.PP
+The default depends on the \fBdetect_prio\fR setting: If \fBdetect_prio\fR is
+\fByes\fR (default), the default priority algorithm is \fBsysfs\fR (except for
+NetAPP E-Series, where it is \fBalua\fR). If \fBdetect_prio\fR is
+\fBno\fR, the default priority algorithm is \fBconst\fR.
.RE
+.
+.
.TP
.B prio_args
Arguments to pass to to the prio function. This only applies to certain
.TP 12
.I weighted
Needs a value of the form
-.I "<hbtl|devname|wwn> <regex1> <prio1> <regex2> <prio2> ..."
+\fI"<hbtl|devname|serial|wwn> <regex1> <prio1> <regex2> <prio2> ..."\fR
+.RS
+.TP 8
.I hbtl
-regex can be of SCSI H:B:T:L format Ex: 1:0:.:. , *:0:0:.
+Regex can be of SCSI H:B:T:L format. For example: 1:0:.:. , *:0:0:.
+.TP
.I devname
-regex can be of device name format Ex: sda , sd.e
-.I wwn
-regex can be of the form
-.I "host_wwnn:host_wwpn:target_wwnn:target_wwpn"
-these values can be looked up through sysfs or by running
-.I mulitpathd show paths format "%N:%R:%n:%r" Ex: 0x200100e08ba0aea0:0x210100e08ba0aea0:.*:.* , .*:.*:iqn.2009-10.com.redhat.msp.lab.ask-06:.*
+Regex can be of device name format. For example: sda , sd.e
.TP
+.I serial
+Regex can be of serial number format. For example: .*J1FR.*324 . The serial can
+be looked up through sysfs or by running multipathd show paths format "%z". For
+example: 0395J1FR904324
+.TP
+.I wwn
+Regex can be of the form \fI"host_wwnn:host_wwpn:target_wwnn:target_wwpn"\fR
+these values can be looked up through sysfs or by running \fImultipathd show paths format
+"%N:%R:%n:%r"\fR. For example: 0x200100e08ba0aea0:0x210100e08ba0aea0:.*:.* , .*:.*:iqn.2009-10.com.redhat.msp.lab.ask-06:.*
+.RE
+.TP 12
+.I path_latency
+Needs a value of the form "io_num=\fI<20>\fR base_num=\fI<10>\fR"
+.RS
+.TP 8
+.I io_num
+The number of read IOs sent to the current path continuously, used to calculate the average path latency.
+Valid Values: Integer, [2, 200].
+.TP
+.I base_num
+The base number value of logarithmic scale, used to partition different priority ranks. Valid Values: Integer,
+[2, 10]. And Max average latency value is 100s, min average latency value is 1us.
+For example: If base_num=10, the paths will be grouped in priority groups with path latency <=1us, (1us, 10us],
+(10us, 100us], (100us, 1ms], (1ms, 10ms], (10ms, 100ms], (100ms, 1s], (1s, 10s], (10s, 100s], >100s.
+.RE
+.TP 12
.I alua
-If
-.I exclusive_pref_bit
-is set, paths with the \fIpreferred path\fR bit set will always
-be in their own path group.
+If \fIexclusive_pref_bit\fR is set, paths with the \fIpreferred path\fR bit
+set will always be in their own path group.
+.TP
+.I sysfs
+If \fIexclusive_pref_bit\fR is set, paths with the \fIpreferred path\fR bit
+set will always be in their own path group.
.TP
.I datacore
+.RS
+.TP 8
.I preferredsds
-???.
+(Mandatory) The preferred "SDS name".
.TP
+.I timeout
+(Optional) The timeout for the INQUIRY, in ms.
+.RE
+.TP 12
.I iet
-.I preferredip
-???.
+.RS
+.TP 8
+.I preferredip=...
+(Mandatory) Th preferred IP address, in dotted decimal notation, for iSCSI targets.
+.RE
.TP
-Default value is: \fB<unset>\fR
+The default is: \fB<unset>\fR
.RE
+.
+.
.TP
.B features
-Specify any device-mapper features to be used. Syntax is
-.I num list
-where
-.I num
-is the number, between 0 and 6, of features in
-.I list.
+Specify any device-mapper features to be used. Syntax is \fInum list\fR
+where \fInum\fR is the number, between 0 and 8, of features in \fIlist\fR.
Possible values for the feature list are:
.RS
.TP 12
.I queue_if_no_path
-Queue IO if no path is active; identical to the
-.I no_path_retry
-keyword.
-.TP
-.I no_partitions
-Disable automatic partitions generation via kpartx.
-.TP
-.I pg_init_retries
-Number of times to retry pg_init, it must be between 1 and 50.
-.TP
-.I pg_init_delay_msecs
-Number of msecs before pg_init retry, it must be between 0 and 60000.
-.TP
-Default value is: \fB0\fR
+(Deprecated, superseded by \fIno_path_retry\fR) Queue I/O if no path is active.
+Identical to the \fIno_path_retry\fR with \fIqueue\fR value. If both this
+feature and \fIno_path_retry\fR are set, the latter value takes
+precedence. See KNOWN ISSUES.
+.TP
+.I pg_init_retries <times>
+(Since kernel 2.6.24) Number of times to retry pg_init, it must be between 1 and 50.
+.TP
+.I pg_init_delay_msecs <msecs>
+(Since kernel 2.6.38) Number of msecs before pg_init retry, it must be between 0 and 60000.
+.TP
+.I queue_mode <mode>
+(Since kernel 4.8) Select the the queueing mode per multipath device.
+<mode> can be \fIbio\fR, \fIrq\fR or \fImq\fR, which corresponds to
+bio-based, request-based, and block-multiqueue (blk-mq) request-based,
+respectively.
+The default depends on the kernel parameter \fBdm_mod.use_blk_mq\fR. It is
+\fImq\fR if the latter is set, and \fIrq\fR otherwise.
+.TP
+The default is: \fB<unset>\fR
.RE
+.
+.
.TP
.B path_checker
The default method used to determine the paths state. Possible values
deprecated, please use \fItur\fR instead.
.TP
.I tur
-Issue a
-.I TEST UNIT READY
-command to the device.
+Issue a \fITEST UNIT READY\fR command to the device.
.TP
.I emc_clariion
(Hardware-dependent)
Query the DGC/EMC specific EVPD page 0xC0 to determine the path state
-for CLARiiON CX/AX and EMC VNX arrays families.
+for CLARiiON CX/AX and EMC VNX and Unity arrays families.
.TP
.I hp_sw
(Hardware-dependent)
.TP
.I rdac
(Hardware-dependent)
-Check the path state for LSI/Engenio/NetApp RDAC class as NetApp E/EF
+Check the path state for LSI/Engenio/NetApp RDAC class as NetApp SANtricity E/EF
Series, and OEM arrays from IBM DELL SGI STK and SUN.
.TP
.I directio
(Hardware-dependent)
Check the path state for HP/COMPAQ Smart Array(CCISS) controllers.
.TP
-Default value is: \fBtur\fR
+.I none
+Do not check the device, fallback to use the values retrieved from sysfs
+.TP
+.I rbd
+Check if the path is in the Ceph blacklist and remap the path if it is.
+.TP
+The default is: \fBtur\fR
.RE
+.
+.
.TP
.B alias_prefix
The \fIuser_friendly_names\fR prefix.
.RS
.TP
-Default value is: \fBmpath\fR
+The default is: \fBmpath\fR
.RE
+.
+.
.TP
.B failback
Tell multipathd how to manage path group failback.
+To select \fIimmediate\fR or a \fIvalue\fR, it's mandatory that the device
+has support for a working prioritizer.
.RS
.TP 12
.I immediate
Do not perform automatic failback.
.TP
.I followover
-Only perform automatic failback when the first path of a pathgroup
-becomes active. This keeps a node from automatically failing back when
+Used to deal with multiple computers accessing the same Active/Passive storage
+devices. Only perform automatic failback when the first path of a pathgroup
+becomes active. This keeps a cluster node from automatically failing back when
another node requested the failover.
.TP
.I values > 0
Deferred failback (time to defer in seconds).
.TP
-Default value is: \fBimmediate\fR
+The default is: \fBmanual\fR
.RE
+.
+.
.TP
.B rr_min_io
-The number of IO to route to a path before switching to the next in
-the same path group. This is only for BIO based multipath.
+Number of I/O requests to route to a path before switching to the next in the
+same path group. This is only for \fIBlock I/O\fR(BIO) based multipath and
+only apply to \fIround-robin\fR path_selector.
.RS
.TP
-Default value is: \fB1000\fR
+The default is: \fB1000\fR
.RE
+.
+.
.TP
.B rr_min_io_rq
-The number of IO requests to route to a path before switching to the
-next in the same path group. This is only for request based multipath.
+Number of I/O requests to route to a path before switching to the next in the
+same path group. This is only for \fIRequest\fR based multipath and
+only apply to \fIround-robin\fR path_selector.
.RS
.TP
-Default value is: \fB1\fR
+The default is: \fB1\fR
.RE
+.
+.
.TP
.B max_fds
Specify the maximum number of file descriptors that can be opened by multipath
-and multipathd. This is equivalent to ulimit \-n. A value of \fImax\fR will set
+and multipathd. This is equivalent to ulimit \-n. A value of \fImax\fR will set
this to the system limit from \fI/proc/sys/fs/nr_open\fR. If this is not set, the
maximum number of open fds is taken from the calling process. It is usually
1024. To be safe, this should be set to the maximum number of paths plus 32,
if that number is greated than 1024.
.RS
.TP
-Default value is: \fBmax\fR
+The default is: \fBmax\fR
.RE
+.
+.
.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
+If set to \fIpriorities\fR the multipath configurator will assign path weights
+as "path prio * rr_min_io". Possible values are
.I priorities
or
-.IR uniform .
+.I uniform .
+Only apply to \fIround-robin\fR path_selector.
.RS
.TP
-Default value is: \fBuniform\fR
+The default is: \fBuniform\fR
.RE
+.
+.
.TP
.B no_path_retry
-Specify the number of retries until disable queueing, or
+Specify what to do when all paths are down. Possible values are:
+.RS
+.TP 12
+.I value > 0
+Number of retries until disable I/O queueing.
+.TP
.I fail
-for immediate failure (no queueing),
+For immediate failure (no I/O queueing).
+.TP
.I queue
-for never stop queueing. If unset no queueing is attempted.
-.RS
+For never stop I/O queueing, similar to \fIqueue_if_no_path\fR. See KNOWN ISSUES.
.TP
-Default value is: \fB<unset>\fR
+The default is: \fBfail\fR
.RE
+.
+.
.TP
.B queue_without_daemon
If set to
.I no
, when multipathd stops, queueing will be turned off for all devices.
-This is useful for devices that set no_path_retry. If a machine is
+This is useful for devices that set no_path_retry. If a machine is
shut down while all paths to a device are down, it is possible to hang waiting
-for IO to return from the device after multipathd has been stopped. Without
+for I/O to return from the device after multipathd has been stopped. Without
multipathd running, access to the paths cannot be restored, and the kernel
-cannot be told to stop queueing IO. Setting queue_without_daemon to
+cannot be told to stop queueing I/O. Setting queue_without_daemon to
.I no
, avoids this problem.
.RS
.TP
-Default value is: \fBno\fR
+The default is: \fBno\fR
.RE
+.
+.
.TP
.B checker_timeout
Specify the timeout to use for path checkers and prioritizers that issue SCSI
commands with an explicit timeout, in seconds.
.RS
.TP
-Default value is: in \fB/sys/block/sd<x>/device/timeout\fR
+The default is: in \fB/sys/block/sd<x>/device/timeout\fR
.RE
+.
+.
.TP
.B flush_on_last_del
If set to
deleted.
.RS
.TP
-Default value is: \fBno\fR
+The default is: \fBno\fR
.RE
+.
+.
.TP
.B user_friendly_names
If set to
.I yes
-, using the bindings file
-.I /etc/multipath/bindings
-to assign a persistent and unique alias to the multipath, in the form of mpath<n>.
-If set to
+, using the bindings file \fI/etc/multipath/bindings\fR to assign a persistent
+and unique alias to the multipath, in the form of mpath<n>. If set to
.I no
use the WWID as the alias. In either case this be will
be overridden by any specific aliases in the \fImultipaths\fR section.
.RS
.TP
-Default value is: \fBno\fR
+The default is: \fBno\fR
.RE
+.
+.
.TP
.B fast_io_fail_tmo
Specify the number of seconds the SCSI layer will wait after a problem has been
-detected on a FC remote port before failing IO to devices on that remote port.
+detected on a FC remote port before failing I/O to devices on that remote port.
This should be smaller than dev_loss_tmo. Setting this to
.I off
will disable the timeout.
.RS
.TP
-Default value is: in \fB5\fR
+The default is: in \fB5\fR
.RE
+.
+.
.TP
.B dev_loss_tmo
Specify the number of seconds the SCSI layer will wait after a problem has
been detected on a FC remote port before removing it from the system. This
can be set to "infinity" which sets it to the max value of 2147483647
seconds, or 68 years. It will be automatically adjusted to the overall
-retry interval
-\fIno_path_retry\fR * \fIpolling_interval\fR
+retry interval \fIno_path_retry\fR * \fIpolling_interval\fR
if a number of retries is given with \fIno_path_retry\fR and the
overall retry interval is longer than the specified \fIdev_loss_tmo\fR value.
-The Linux kernel will cap this value to \fI300\fR if \fIfast_io_fail_tmo\fR
-is not set.
+The Linux kernel will cap this value to \fI600\fR if \fIfast_io_fail_tmo\fR
+is not set. See KNOWN ISSUES.
.RS
.TP
-Default value is: \fB600\fR
+The default is: \fB600\fR
.RE
+.
+.
.TP
.B bindings_file
-The full pathname of the binding file to be used when the user_friendly_names option is set.
+The full pathname of the binding file to be used when the user_friendly_names
+option is set.
.RS
.TP
-Default value is: \fB/etc/multipath/bindings\fR
+The default is: \fB/etc/multipath/bindings\fR
.RE
+.
+.
.TP
.B wwids_file
The full pathname of the WWIDs file, which is used by multipath to keep track
of the WWIDs for LUNs it has created multipath devices on in the past.
.RS
.TP
-Default value is: \fB/etc/multipath/wwids\fR
+The default is: \fB/etc/multipath/wwids\fR
.RE
+.
+.
+.TP
+.B prkeys_file
+The full pathname of the prkeys file, which is used by multipathd to keep
+track of the persistent reservation key used for a specific WWID, when
+\fIreservation_key\fR is set to \fBfile\fR.
+.RS
+.TP
+The default is \fB/etc/multipath/prkeys\fR
+.RE
+.
+.
.TP
.B log_checker_err
If set to
, multipathd always logs the path checker error at logging level 2.
.RS
.TP
-Default value is: \fBalways\fR
+The default is: \fBalways\fR
.RE
+.
+.
.TP
.B reservation_key
-This is the service action reservation key used by mpathpersist. It must be
+This is the service action reservation key used by mpathpersist. It must be
set for all multipath devices using persistent reservations, and it must be
the same as the RESERVATION KEY field of the PERSISTENT RESERVE OUT parameter
list which contains an 8-byte value provided by the application client to the
device server to identify the I_T nexus.
.RS
-.TP
-Default value is: \fB<unset>\fR
+.PP
+Alternatively, this can be set to \fBfile\fR, which will store the RESERVATION
+KEY registered by mpathpersist in the \fIprkeys_file\fR. multipathd will then
+use this key to register additional paths as they appear. When the
+registration is removed, the RESERVATION KEY is removed from the
+\fIprkeys_file\fR.
+.TP
+The default is: \fB<unset>\fR
.RE
+.
+.
.TP
.B retain_attached_hw_handler
-If set to
+(Obsolete for kernels >= 4.3) If set to
.I yes
and the SCSI layer has already attached a hardware_handler to the device,
multipath will not force the device to use the hardware_handler specified by
mutipath.conf. If the SCSI layer has not attached a hardware handler,
multipath will continue to use its configured hardware handler.
.RS
-.TP
-Default value is: \fByes\fR
+.PP
+The default is: \fByes\fR
+.PP
+\fBImportant Note:\fR Linux kernel 4.3 or newer always behaves as if
+\fB"retain_attached_hw_handler yes"\fR was set.
.RE
+.
+.
.TP
.B detect_prio
If set to
.I yes
, multipath will try to detect if the device supports SCSI-3 ALUA. If so, the
-device will automatically use the
-.I sysfs
-prioritizer if the required sysfs attributes
-.I access_state
-and
-.I preferred_path
-are supported, or the
-.I alua
-prioritizer if not. If set to
+device will automatically use the \fIsysfs\fR prioritizer if the required sysf
+attributes \fIaccess_state\fR and \fIpreferred_path\fR are supported, or the
+\fIalua\fR prioritizer if not. If set to
.I no
, the prioritizer will be selected as usual.
.RS
.TP
-Default value is: \fByes\fR
+The default is: \fByes\fR
.RE
+.
+.
+.TP
+.B detect_checker
+if set to
+.I yes
+, multipath will try to detect if the device supports SCSI-3 ALUA. If so, the
+device will automatically use the \fItur\fR checker. If set to
+.I no
+, the checker will be selected as usual.
+.RS
+.TP
+The default is: \fByes\fR
+.RE
+.
+.
.TP
.B force_sync
If set to
multipathd checkers running in parallel causes significant CPU pressure.
.RS
.TP
-Default value is: \fBno\fR
+The default is: \fBno\fR
.RE
+.
+.
.TP
-.B strict_timinig
+.B strict_timing
If set to
.I yes
, multipathd will start a new path checker loop after exactly one second,
-so that each path check will occur at exactly
-.I polling_interval
+so that each path check will occur at exactly \fIpolling_interval\fR
seconds. On busy systems path checks might take longer than one second;
here the missing ticks will be accounted for on the next round.
-A warning will be printed if path checks take longer than
-.I polling_interval
+A warning will be printed if path checks take longer than \fIpolling_interval\fR
seconds.
.RS
.TP
-Default value is: \fBno\fR
+The default is: \fBno\fR
.RE
+.
+.
.TP
.B deferred_remove
If set to
will be canceled.
.RS
.TP
-Default value is: \fBno\fR
+The default is: \fBno\fR
.RE
+.
+.
.TP
.B partition_delimiter
If this value is not set, when multipath renames a device, it will act just
the \fI-p\fR option is used, and always add delimiter.
.RS
.TP
-Default value is: \fB<unset>\fR
+The default is: \fB<unset>\fR
.RE
+.
+.
.TP
.B config_dir
If set to anything other than "", multipath will search this directory
config_dir must either be "" or a fully qualified directory name.
.RS
.TP
-Default value is: \fB/etc/multipath/conf.d/\fR
+The default is: \fB/etc/multipath/conf.d/\fR
+.RE
+.
+.
+.TP
+.B marginal_path_double_failed_time
+One of the four parameters of supporting path check based on accounting IO
+error such as intermittent error. When a path failed event occurs twice in
+\fImarginal_path_double_failed_time\fR seconds due to an IO error and all the
+other three parameters are set, multipathd will fail the path and enqueue
+this path into a queue of which members are sent a couple of continuous
+direct reading asynchronous IOs at a fixed sample rate of 10HZ to start IO
+error accounting process.
+.RS
+.TP
+The default is: \fBno\fR
+.RE
+.
+.
+.TP
+.B marginal_path_err_sample_time
+One of the four parameters of supporting path check based on accounting IO
+error such as intermittent error. If it is set to a value no less than 120,
+when a path fail event occurs twice in \fImarginal_path_double_failed_time\fR
+second due to an IO error, multipathd will fail the path and enqueue this
+path into a queue of which members are sent a couple of continuous direct
+reading asynchronous IOs at a fixed sample rate of 10HZ to start the IO
+accounting process for the path will last for
+\fImarginal_path_err_sample_time\fR.
+If the rate of IO error on a particular path is greater than the
+\fImarginal_path_err_rate_threshold\fR, then the path will not reinstate for
+\fImarginal_path_err_recheck_gap_time\fR seconds unless there is only one
+active path. After \fImarginal_path_err_recheck_gap_time\fR expires, the path
+will be requeueed for rechecking. If checking result is good enough, the
+path will be reinstated.
+.RS
+.TP
+The default is: \fBno\fR
+.RE
+.
+.
+.TP
+.B marginal_path_err_rate_threshold
+The error rate threshold as a permillage (1/1000). One of the four parameters
+of supporting path check based on accounting IO error such as intermittent
+error. Refer to \fImarginal_path_err_sample_time\fR. If the rate of IO errors
+on a particular path is greater than this parameter, then the path will not
+reinstate for \fImarginal_path_err_rate_threshold\fR seconds unless there is
+only one active path.
+.RS
+.TP
+The default is: \fBno\fR
.RE
+.
+.
+.TP
+.B marginal_path_err_recheck_gap_time
+One of the four parameters of supporting path check based on accounting IO
+error such as intermittent error. Refer to
+\fImarginal_path_err_sample_time\fR. If this parameter is set to a positive
+value, the failed path of which the IO error rate is larger than
+\fImarginal_path_err_rate_threshold\fR will be kept in failed state for
+\fImarginal_path_err_recheck_gap_time\fR seconds. When
+\fImarginal_path_err_recheck_gap_time\fR seconds expires, the path will be
+requeueed for checking. If checking result is good enough, the path will be
+reinstated, or else it will keep failed.
+.RS
+.TP
+The default is: \fBno\fR
+.RE
+.
+.
.TP
.B delay_watch_checks
If set to a value greater than 0, multipathd will watch paths that have
-recently become valid for this many checks. If they fail again while they are
+recently become valid for this many checks. If they fail again while they are
being watched, when they next become valid, they will not be used until they
-have stayed up for
-.I delay_wait_checks
-checks.
+have stayed up for \fIdelay_wait_checks\fR checks.
.RS
.TP
-Default value is: \fBno\fR
+The default is: \fBno\fR
.RE
+.
+.
.TP
.B delay_wait_checks
If set to a value greater than 0, when a device that has recently come back
-online fails again within
-.I delay_watch_checks
-checks, the next time it comes back online, it will marked and delayed, and not
-used until it has passed
-.I delay_wait_checks
-checks.
+online fails again within \fIdelay_watch_checks\fR checks, the next time it
+comes back online, it will marked and delayed, and not used until it has passed
+\fIdelay_wait_checks\fR checks.
.RS
.TP
-Default value is: \fBno\fR
+The default is: \fBno\fR
.RE
+.
+.
.TP
.B find_multipaths
If set to
while find_multipaths was set (even if that multipath device doesn't currently
exist).
Whenever a multipath device is created with find_multipaths set, multipath will
-remeber the WWID of the device, so that it will automatically create the
+remember the WWID of the device, so that it will automatically create the
device again, as soon as it sees a path with that WWID. This should allow most
users to have multipath automatically choose the correct paths to make into
multipath devices, without having to edit the blacklist.
.RS
.TP
-Default value is: \fBno\fR
+The default is: \fBno\fR
.RE
+.
+.
.TP
.B uxsock_timeout
CLI receive timeout in milliseconds. For larger systems CLI commands
those issues.
.RS
.TP
-Default value is: \fB1000\fR
+The default is: \fB1000\fR
.RE
+.
+.
.TP
.B retrigger_tries
Sets the number of times multipathd will try to retrigger a uevent to get the
WWID.
.RS
.TP
-Default value is: \fB3\fR
+The default is: \fB3\fR
.RE
+.
+.
.TP
.B retrigger_delay
Sets the amount of time, in seconds, to wait between retriggers.
.RS
.TP
-Default value is: \fB10\fR
+The default is: \fB10\fR
.RE
+.
+.
.TP
.B missing_uev_wait_timeout
Controls how many seconds multipathd will wait, after a new multipath device
on a device until it receives a change uevent from the initial table load.
.RS
.TP
-Default value is: \fB30\fR
+The default is: \fB30\fR
+.RE
+.
+.
+.TP
+.B skip_kpartx
+If set to
+.I yes
+, kpartx will not automatically create partitions on the device.
+.RS
+.TP
+The default is: \fBno\fR
+.RE
+.
+.
+.TP
+.B disable_changed_wwids
+If set to \fIyes\fR, multipathd will check the path wwid on change events, and
+if it has changed from the wwid of the multipath device, multipathd will
+disable access to the path until the wwid changes back.
+.RS
+.TP
+The default is: \fBno\fR
+.RE
+.
+.
+.TP
+.B remove_retries
+This sets how may times multipath will retry removing a device that is in-use.
+Between each attempt, multipath will sleep 1 second.
+.RS
+.TP
+The default is: \fB0\fR
+.RE
+.
+.
+.TP
+.B max_sectors_kb
+Sets the max_sectors_kb device parameter on all path devices and the multipath
+device to the specified value.
+.RS
+.TP
+The default is: \fB<device dependent>\fR
+.RE
+.
+.
+.TP
+.B ghost_delay
+Sets the number of seconds that multipath will wait after creating a device
+with only ghost paths before marking it ready for use in systemd. This gives
+the active paths time to appear before the multipath runs the hardware handler
+to switch the ghost paths to active ones. Setting this to \fI0\fR or \fIon\fR
+makes multipath immediately mark a device with only ghost paths as ready.
+.RS
+.TP
+The default is \fBno\fR
.RE
.
+.
+.\" ----------------------------------------------------------------------------
.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.
+.\" ----------------------------------------------------------------------------
+.
+The \fIblacklist\fR 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 devnode
Regular expression of the device nodes to be excluded.
+.RS
+.TP
+The default is: \fB^(ram|raw|loop|fd|md|dm-|sr|scd|st|dcssblk)[0-9]\fR and \fB^(td|hd|vd)[a-z]\fR
+.RE
.TP
.B wwid
The \fIWorld Wide Identification\fR of a device.
and
.B product
keywords. For a full description of these keywords please see the
-.I devices
-section description.
+\fIdevices\fR section description.
+.
+.
+.\" ----------------------------------------------------------------------------
.SH "blacklist_exceptions section"
-The
-.I blacklist_exceptions
-section is used to revert the actions of the
-.I blacklist
-section, for example to include specific device in the
+.\" ----------------------------------------------------------------------------
+.
+The \fIblacklist_exceptions\fR section is used to revert the actions of the
+\fIblacklist\fR section. For example to include specific device in the
multipath topology. This allows one to selectively include devices which
-would normally be excluded via the
-.I blacklist
-section.
+would normally be excluded via the \fIblacklist\fR section.
.LP
+.
+.
The following keywords are recognized:
.TP 17
.B devnode
Regular expression of the udev property to be whitelisted.
.RS
.TP
-Default value is: \fB(ID_WWN|SCSI_IDENT_.*)\fR
+The default is: \fB(SCSI_IDENT_|ID_WWN)\fR
.RE
.TP
.B device
.B vendor
and
.B product
-keywords. For a full description of these keywords please see the
-.I devices
+keywords. For a full description of these keywords please see the \fIdevices\fR
section description.
.LP
-The
-.I property
-blacklist and whitelist handling is different from the usual handling
-in the sense that the whitelist
-.I has
-to be set, otherwise the device will be blacklisted.
-In these cases the message
-.I blacklisted, udev property missing
-will be displayed.
+The \fIproperty\fR blacklist and whitelist handling is different from the usual
+handling in the sense that the whitelist \fIhas\fR to be set, otherwise the
+device will be blacklisted. In these cases the message \fIblacklisted, udev
+property missing\fR will be displayed.
+.
+.
+.\" ----------------------------------------------------------------------------
.SH "multipaths section"
-The only recognized attribute for the
-.I multipaths
-section is the
-.I multipath
-subsection.
+.\" ----------------------------------------------------------------------------
+.
+The only recognized attribute for the \fImultipaths\fR section is the
+\fImultipath\fR subsection.
.LP
-The
-.I multipath
-subsection recognizes the following attributes:
+.
+.
+The \fImultipath\fR subsection recognizes the following attributes:
.TP 17
.B wwid
(Mandatory) Index of the container.
.TP
.B alias
-(Optional) Symbolic name for the multipath map.
+Symbolic name for the multipath map.
.LP
+.
+.
The following attributes are optional; if not set the default values
-are taken from the
-.I defaults
-or
-.I devices
-section:
+are taken from the \fIdefaults\fR or \fIdevices\fR section:
.sp 1
.PD .1v
.RS
.TP
.B deferred_remove
.TP
+.B marginal_path_err_sample_time
+.TP
+.B marginal_path_err_rate_threshold
+.TP
+.B marginal_path_err_recheck_gap_time
+.TP
+.B marginal_path_double_failed_time
+.TP
.B delay_watch_checks
.TP
.B delay_wait_checks
+.TP
+.B skip_kpartx
+.TP
+.B max_sectors_kb
+.TP
+.B ghost_delay
.RE
.PD
.LP
+.
+.
+.\" ----------------------------------------------------------------------------
.SH "devices section"
-The only recognized attribute for the
-.I devices
-section is the
-.I device
+.\" ----------------------------------------------------------------------------
+.
+The only recognized attribute for the \fIdevices\fR section is the \fIdevice\fR
subsection.
.LP
-The
-.I device
-subsection recognizes the following attributes:
+.
+.
+The \fIdevice\fR subsection recognizes the following attributes:
+.TP
+vendor, product, revision and product_blacklist are POSIX Extended regex.
.TP 17
.B vendor
(Mandatory) Vendor identifier.
(Mandatory) Product identifier.
.TP
.B revision
-(Optional) Revision identfier.
+Revision identfier.
.TP
.B product_blacklist
-(Optional) Product strings to blacklist for this vendor.
+Product strings to blacklist for this vendor.
.TP
.B alias_prefix
-(Optional) The user_friendly_names prefix to use for this
+The user_friendly_names prefix to use for this
device type, instead of the default "mpath".
.TP
.B hardware_handler
-(Optional) The hardware handler to use for this device type.
+The hardware handler to use for this device type.
The following hardware handler are implemented:
.RS
.TP 12
.I 1 emc
(Hardware-dependent)
-Hardware handler for DGC class arrays as CLARiiON CX/AX and EMC VNX families.
+Hardware handler for DGC class arrays as CLARiiON CX/AX and EMC VNX and Unity
+families.
.TP
.I 1 rdac
(Hardware-dependent)
-Hardware handler for LSI/Engenio/NetApp RDAC class as NetApp E/EF
+Hardware handler for LSI/Engenio/NetApp RDAC class as NetApp SANtricity E/EF
Series, and OEM arrays from IBM DELL SGI STK and SUN.
.TP
.I 1 hp_sw
.I 1 alua
(Hardware-dependent)
Hardware handler for SCSI-3 ALUA compatible arrays.
-.TP
-Default value is: \fB<unset>\fR
+.PP
+The default is: \fB<unset>\fR
+.PP
+\fBImportant Note:\fR Linux kernels 4.3 and newer automatically attach a device
+handler to known devices (which includes all devices supporting SCSI-3 ALUA)
+and disallow changing the handler
+afterwards. Setting \fBhardware_handler\fR for such devices on these kernels
+has no effect.
.RE
+.
+.
.LP
The following attributes are optional; if not set the default values
-are taken from the
-.I defaults
+are taken from the \fIdefaults\fR
section:
.sp 1
.PD .1v
.TP
.B detect_prio
.TP
+.B detect_checker
+.TP
.B deferred_remove
.TP
+.B marginal_path_err_sample_time
+.TP
+.B marginal_path_err_rate_threshold
+.TP
+.B marginal_path_err_recheck_gap_time
+.TP
+.B marginal_path_double_failed_time
+.TP
.B delay_watch_checks
.TP
.B delay_wait_checks
+.TP
+.B skip_kpartx
+.TP
+.B max_sectors_kb
+.TP
+.B ghost_delay
.RE
.PD
.LP
+.
+.
+.\" ----------------------------------------------------------------------------
.SH "overrides section"
+.\" ----------------------------------------------------------------------------
+.
The overrides section recognizes the following optional attributes; if not set
-the values are taken from the
-.I devices
-or
-.I defaults
-sections:
+the values are taken from the \fIdevices\fR or \fIdefaults\fR sections:
.sp 1
.PD .1v
.RS
.TP
.B detect_prio
.TP
+.B detect_checker
+.TP
.B deferred_remove
.TP
+.B marginal_path_err_sample_time
+.TP
+.B marginal_path_err_rate_threshold
+.TP
+.B marginal_path_err_recheck_gap_time
+.TP
+.B marginal_path_double_failed_time
+.TP
.B delay_watch_checks
.TP
.B delay_wait_checks
+.TP
+.B skip_kpartx
+.TP
+.B ghost_delay
.RE
.PD
.LP
+.
+.
+.\" ----------------------------------------------------------------------------
.SH "WWID generation"
+.\" ----------------------------------------------------------------------------
+.
Multipath uses a \fIWorld Wide Identification\fR (WWID) to determine
which paths belong to the same device. Each path presenting the same
WWID is assumed to point to the same device.
If none of the \fIgetuid_callout\fR or \fIuid_attribute\fR parameters
are present multipath will try to use the sysfs attribute
\fIvpd_pg83\fR to generate the WWID.
+.
+.
+.\" ----------------------------------------------------------------------------
.SH "KNOWN ISSUES"
-The usage of
-.I queue_if_no_path
-option can lead to
-.I 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
-.I no_path_retry
-option instead.
+.\" ----------------------------------------------------------------------------
+.
+The usage of \fIqueue_if_no_path\fR option can lead to \fID state\fR
+processes being hung and not killable in situations where all the paths to the
+LUN go offline. It is advisable to use the \fIno_path_retry\fR option instead.
.P
-The use of
-.I queue_if_no_path
-or
-.I no_path_retry
-might lead to a deadlock if the
-.I dev_loss_tmo
-setting results in a device being removed while I/O is still queued.
-The multipath daemon will update the
-.I dev_loss_tmo
+The use of \fIqueue_if_no_path\fR or \fIno_path_retry\fR might lead to a
+deadlock if the \fIdev_loss_tmo\fR setting results in a device being removed
+while I/O is still queued. The multipath daemon will update the \fIdev_loss_tmo\fR
setting accordingly to avoid this deadlock. Hence if both values are
-specified the order of precedence is
-.I no_path_retry, queue_if_no_path, dev_loss_tmo.
-
+specified the order of precedence is \fIno_path_retry, queue_if_no_path, dev_loss_tmo\fR.
+.
+.
+.\" ----------------------------------------------------------------------------
.SH "SEE ALSO"
+.\" ----------------------------------------------------------------------------
+.
.BR udev (8),
.BR dmsetup (8),
.BR multipath (8),
.BR multipathd (8).
-
+.
+.
+.\" ----------------------------------------------------------------------------
.SH AUTHORS
-.I multipath-tools
-was developed by Christophe Varoqui, <christophe.varoqui@opensvc.com> and others.
+.\" ----------------------------------------------------------------------------
+.
+\fImultipath-tools\fR was developed by Christophe Varoqui, <christophe.varoqui@opensvc.com>
+and others.
+.\" EOF
projects / platform / upstream / multipath-tools.git / blobdiff