Multipath in HP UX

Multipath:

A simple example would be a SCSI disk connected to two SCSI controllers on the same computer or a disk connected to two Fibre Channel ports. Should one controller, port or switch fail, the operating system can route I/O through the remaining controller transparently to the application, with no changes visible to the applications, other than perhaps incremental latency.

Features of Multipath:

    * Dynamic load balancing
    * Traffic shaping
    * Automatic path management
    * Dynamic reconfiguration

How to find multipath on hp ux ??


1.pvlinks

   # strings /etc/lvmtab
   # vgdisplay -v vgname

2.Native Multipathing (11.31) (agile device name)

  # ioscan -m dsf h/w address 
    
    Examble : ioscan -m dsf/dev/rdisk/disk586
              Persistent DSF      Legacy DSF(s)
          =============================================
              /dev/rdisk/disk586  /dev/rdsk/c15t0d0
                                  /dev/rdsk/c16t0d0


  # scsimgr -D lun_map (which will give the number of paths to that lun)

  # ioscan -kfnNC  (will show the persistent device file in 11.31)

  # evainfo (EVA) and xpinfo (XP) - commands will show the multipaths for luns.

1 comments:

  1. Great post.

    I have also found for fiber, using a combination of "fcmsutil" and "ioscan" can give you a lot of great detail:

    e.g. on a system I have here
    # fcmsutil /dev/fcd2
    ..
    Hardware Path is = 0/3/1/0
    ..
    # fcmsutil /dev/fcd3
    ..
    Hardware Path is = 0/3/1/1
    ..

    Then
    # ioscan -f -n -C disk
    ..
    disk 6 0/3/1/0.1.7.0.0.0.0 sdisk CLAIMED DEVICE IBM 1722-600
    /dev/dsk/c9t0d0 /dev/rdsk/c9t0d0
    ..
    disk 30 0/3/1/1.1.7.0.0.0.0 sdisk CLAIMED DEVICE IBM 1722-600
    /dev/dsk/c8t0d0 /dev/rdsk/c8t0d0
    ..

    So two disks, one each on the hardware paths for the HBAs

    Finally

    # ioscan -f -n -N -C disk
    ..
    disk 46 64000/0xfa00/0xe esdisk CLAIMED DEVICE IBM 1722-600
    /dev/disk/disk46 /dev/rdisk/disk46
    ..

    That's the only IBM disk that shows up and it is the combined path for the two disks previous

    Anyway.. :)
    Thanks!

    ReplyDelete

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