Provided by: multipath-tools_0.4.9-3ubuntu5_amd64 bug

NAME

       multipath.conf - multipath daemon configuration file

DESCRIPTION

       multipath.conf is the configuration file for the multipath daemon. It is used to overwrite
       the built-in configuration table of multipathd.   Any  line  whose  first  non-white-space
       character is a '#' is considered a comment line. Empty lines are ignored.

SYNTAX

       The configuration file contains entries of the form:

              <section> {
                     <attribute> <value>
                     ...
                     <subsection> {
                            <attribute> <value>
                            ...
                     }
              }

       Each  section  contains one or more attributes or subsections. The recognized keywords for
       attributes or subsections depend on the section in which they occor.

       The following section keywords are recognized:

       defaults         This section  defines  default  values  for  attributes  which  are  used
                        whenever no specific setting is given.

       blacklist        This  section defines which devices should be excluded from the multipath
                        topology discovery.

       blacklist_exceptions
                        This section defines which devices should be included  in  the  multipath
                        topology discovery, despite being listed in the blacklist section.

       multipaths       This  section  defines  the  multipath  topologies. They are indexed by a
                        World Wide Identifier(wwid), which is the result  of  the  getuid_callout
                        program.

       devices          This section defines the device-specific settings.

defaults section

       The defaults section recognizes the following keywords:

       polling_interval interval  between  two  path  checks  in seconds For properly functioning
                        paths, the interval between  checks  will  gradually  increase  to  (4  *
                        polling_interval); default is 5

       udev_dir         directory where udev creates its device nodes; default is /dev

       verbosity        default  verbosity.  Higher  values  increase  the verbosity level. Valid
                        levels are between 0 and 6; default is 2

       selector         The default path selector algorithm to  use;  they  are  offered  by  the
                        kernel multipath target. The only currently implemented is round-robin 0

       path_grouping_policy
                        The  default  path  grouping  policy  to apply to unspecified multipaths.
                        Possible values are

                        failover    1 path per priority group

                        multibus    all paths in 1 priority group

                        group_by_serial
                                    1 priority group per serial number

                        group_by_prio
                                    1  priority  group  per  priority   value.   Priorities   are
                                    determined  by  callout  programs specified as a global, per-
                                    controller or per-multipath option in the configuration file.

                        group_by_node_name
                                    1 priority group per target node name. Target node names  are
                                    fetched in /sys/class/fc_transport/target*/node_name.

                        Default value is multibus.

       getuid_callout   The  default  program  and  args  to  callout  to  obtain  a  unique path
                        identifier. Should be specified with an absolute path. Default  value  is
                        /lib/udev/scsi_id --whitelisted --device=/dev/%n

       prio_callout     The  default program and args to callout to obtain a path priority value.
                        The specified program will be executed and should return a numeric  value
                        specifying  the  relative  priority  of  this  path. Higher number have a
                        higher priority. A '%n' in the command  line  will  be  expanded  to  the
                        device  name, a '%b' will be expanded to the device number in major:minor
                        format.  none is a valid value. Currently  the  following  path  priority
                        programs are implemented:

                        mpath_prio_emc /dev/%n
                                    Generate the path priority for EMC arrays

                        mpath_prio_alua /dev/%n
                                    Generate the path priority based on the SCSI-3 ALUA settings.

                        mpath_prio_netapp /dev/%n
                                    Generate the path priority for NetApp arrays.

                        mpath_prio_rdac /dev/%n
                                    Generate the path priority for LSI/Engenio RDAC controller.

                        mpath_prio_hp_sw /dev/%n
                                    Generate  the  path  priority  for  Compaq/HP  controller  in
                                    active/standby mode.

                        mpath_prio_hds_modular %b
                                    Generate the path priority for Hitachi  HDS  Modular  storage
                                    arrays.

                        Default value is none.

       features         Specify  any  device-mapper features to be used. The most common of these
                        features is 1 queue_if_no_path Note that this can also  be  set  via  the
                        no_path_retry keyword.

       path_checker     The  default  method  used to determine the paths' state. Possible values
                        are

                        readsector0 Read the first sector of the device

                        tur         Issue a TEST UNIT READY command to the device.

                        emc_clariion
                                    Query the EMC Clariion specific EVPD page 0xC0  to  determine
                                    the path state.

                        hp_sw       Check   the   path   state   for   HP   storage  arrays  with
                                    Active/Standby firmware.

                        rdac        Check the path state for LSI/Engenio RDAC storage controller.

                        directio    Read the first sector with direct I/O.

                        Default value is readsector0.

       failback         Tell the daemon to manage path group failback, or not to. 0 or  immediate
                        means immediate failback, values >0 means deferred failback (in seconds).
                        manual means no failback. Default value is manual

       rr_min_io        The number of IO to route to a path before switching to the next  in  the
                        same path group. Default is 1000

       rr_weight        If  set to priorities the multipath configurator will assign path weights
                        as "path prio * rr_min_io". Possible values are  priorities  or  uniform.
                        Default is uniform.

       no_path_retry    Specify  the  number  of  retries  until  disable  queueing,  or fail for
                        immediate failure (no queueing), queue for never stop  queueing.  Default
                        is 0.

       user_friendly_names
                        If set to yes , using the bindings file /etc/multipath/bindings to assign
                        a persistent and unique alias to the multipath, in the form of  mpath<n>.
                        If  set  to  no use the WWID as the alias. In either case this be will be
                        overridden by any specific aliases in the multipaths section.  Default is
                        no

       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
                        max  will set this to the system limit from /proc/sys/fs/nr_open. 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.

       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.  This should be smaller than dev_loss_tmo. Setting this
                        to off will disable the timeout.

       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.

       queue_without_daemon
                        If set to 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 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 multipathd running, access to the paths  cannot  be
                        restored,  and  the  kernel  cannot  be told to stop queueing IO. Setting
                        queue_without_daemon to no , avoids this problem. Default is yes

blacklist section

       The 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 following keywords are recognized:

       wwid             The World Wide Identification of a device.

       devnode          Regular expression of the device nodes to be excluded.

       device           Subsection for the device description.  This  subsection  recognizes  the
                        vendor  and  product  keywords.  For a full description of these keywords
                        please see the devices section description.

blacklist_exceptions section

       The blacklist_exceptions section is used to revert the actions of the  blacklist  section,
       ie  to  include  specific  device  in  the  multipath topology. This allows to selectively
       include devices which would normally be excluded via the blacklist section.

       The following keywords are recognized:

       wwid             The World Wide Identification of a device.

       devnode          Regular expression of the device nodes to be excluded.

       device           Subsection for the device description.  This  subsection  recognizes  the
                        vendor  and  product  keywords.  For a full description of these keywords
                        please see the devices section description.

multipaths section

       The only recognized attribute for the multipaths section is the multipath subsection.

       The multipath subsection recognizes the following attributes:

       wwid             Index of the container. Mandatory for this subsection.

       alias            (Optional) symbolic name for the multipath map.

       The following attributes are optional; if not set the default values are  taken  from  the
       defaults section:

              path_grouping_policy
              path_selector
              failback
              no_path_retry
              rr_min_io

devices section

       The only recognized attribute for the devices section is the device subsection.

       The device subsection recognizes the following attributes:

       vendor           (Mandatory) Vendor identifier

       product          (Mandatory) Product identifier

       product_blacklist
                        Product strings to blacklist for this vendor

       hardware_handler (Optional)  The  hardware  handler  to  use  for  this  device type.  The
                        following hardware handler are implemented:

                        1 emc       Hardware handler for EMC storage arrays.

       The following attributes are optional; if not set the default values are  taken  from  the
       defaults section:

              path_grouping_policy
              getuid_callout
              path_selector
              path_checker
              features
              prio_callout
              failback
              rr_weight
              no_path_retry
              rr_min_io
              fast_io_fail_tmo
              dev_loss_tmo

KNOWN ISSUES

       The  usage  of  queue_if_no_path  option  can lead to 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 no_path_retry option instead.

SEE ALSO

       udev(8), dmsetup(8) multipath(8) multipathd(8)

AUTHORS

       multipath  was  developed  by  Christophe  Varoqui,  <christophe.varoqui@opensvc.com>  and
       others.

                                         30 November 2006                       MULTIPATH.CONF(5)