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Hi there, My Redhat server 6 has to luns coming from the storage with are both multipathed as shown multipath -ll mpathc (360060e800562cf00000062cf0000092d) dm-1 HITACHI,OPEN-V size=50G features='1 queue_if_no_path' hwhandler='0' wp=rw ...
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  1. #1
    Just Joined!
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    Jan 2013
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    multipathing in Redhat 6


    Hi there,

    My Redhat server 6 has to luns coming from the storage with are both multipathed as shown

    multipath -ll

    mpathc (360060e800562cf00000062cf0000092d) dm-1 HITACHI,OPEN-V
    size=50G features='1 queue_if_no_path' hwhandler='0' wp=rw
    `-+- policy='round-robin 0' prio=1 status=active
    |- 3:0:0:1 sdd 8:48 active ready running
    `- 1:0:0:1 sde 8:64 active ready running
    mpathb (360060e800562cf00000062cf0000091b) dm-0 HITACHI,OPEN-V
    size=50G features='1 queue_if_no_path' hwhandler='0' wp=rw
    `-+- policy='round-robin 0' prio=1 status=active
    |- 3:0:0:0 sdb 8:16 active ready running
    `- 1:0:0:0 sdc 8:32 active ready running


    What i want to know is ,does this configuration mean both the paths are working i.e; load balancing is on,If YES,
    I want to stop one path and use it only when the primary path fails.Kindly suggest on this

    I will really appreciate the help


    Regards
    Rafi

  2. #2
    Linux Guru
    Join Date
    Nov 2007
    Posts
    1,763
    Google "linux multipath" and edit the multipath.conf to set the path_grouping_policy.

  3. #3
    Just Joined!
    Join Date
    Jan 2013
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    3
    Dear HROadmin26,
    What i Read from Red hat official document is :
    path_grouping_policy Specifies the default path grouping policy to apply to unspecified
    multipaths.
    Possible values include:
    Failover: 1 path per priority group.
    multibus: all valid paths in 1 priority group.
    group_by_serial: 1 priority group per detected serial number.
    group_by_prio: 1 priority group per path priority value. Priorities
    are determined by callout programs specified as global, per-controller, or per-multipath options.
    group_by_node_name: 1 priority group per target node name.
    Target node names are fetched in
    /sys/class/fc_transport/target*/node_name.
    The default value is failover.


    What i am unable to understand is the priority group...In my case as shown above both the luns and paths have prio as 1,Do i have to chane the priority
    of the of paths individually and how?

    Regards

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