Dynamic Multi-Pathing 8.0.1 Administrator's Guide - Windows

Last Published:
Product(s): InfoScale & Storage Foundation (8.0.1)
Platform: Windows
  1. Understanding DMPW
    1.  
      DMP overview
    2.  
      Major features of Dynamic Multi-Pathing
    3. How DMP works
      1. How DMP monitors I/O on paths
        1.  
          Path failover mechanism
      2.  
        Load balancing
      3.  
        DMP in a clustered environment
    4.  
      Multiple paths to disk arrays
    5.  
      Device discovery
  2. Setting up DMPW
    1.  
      Active/Active and Active/Passive settings
    2. Active/Active and Active/Passive settings in a cluster environment
      1.  
        DMP DSMs
      2.  
        SCSI-3 PGR technology
      3.  
        Enabling SCSI-3 PGR
    3. Add and remove paths
      1.  
        Adding a path
      2.  
        Removing a path
    4. Specify load balancing settings and the primary path
      1.  
        Specifying load balancing settings for an array
      2.  
        Specifying load balancing settings for a disk
      3.  
        Specifying the primary path for an array or disk
    5. Configuring DSMs without storage connection
      1.  
        Specify DSM settings without storage connection
  3. Administering DMPW
    1.  
      About administering DMP
    2. DMP DSMs menus
      1.  
        Displaying the menu for arrays
      2.  
        Commands for arrays
      3.  
        Displaying the menu for disks
      4.  
        Commands for paths of a disk
      5.  
        Statistics monitoring
      6.  
        Clear performance statistics
      7.  
        Device settings
      8.  
        Set primary path
      9.  
        Properties
    3. View array, disk, and path status
      1.  
        Array status
      2.  
        Device status
      3.  
        Path status
    4. vxdmpadm
      1.  
        vxdmpadm dsminfo
      2.  
        vxdmpadm arrayinfo
      3.  
        vxdmpadm deviceinfo
      4.  
        vxdmpadm pathinfo
      5.  
        vxdmpadm arrayperf
      6.  
        vxdmpadm deviceperf
      7.  
        vxdmpadm pathperf
      8.  
        vxdmpadm allperf
      9.  
        vxdmpadm iostat
      10.  
        vxdmpadm cleardeviceperf
      11.  
        vxdmpadm cleararrayperf
      12.  
        vxdmpadm clearallperf
      13.  
        vxdmpadm setdsmscsi3
      14.  
        vxdmpadm setarrayscsi3
      15.  
        vxdmpadm setattr dsm
      16.  
        vxdmpadm setattr array
      17.  
        vxdmpadm setattr device
      18.  
        vxdmpadm setattr path
      19.  
        vxdmpadm set isislog
      20.  
        vxdmpadm rescan
      21.  
        vxdmpadm disk list
      22.  
        vxdmpadm getdsmattrib
      23.  
        vxdmpadm getmpioparam
      24.  
        vxdmpadm setmpioparam
  4. Performance tuning
    1.  
      Specifying control timer settings for an array
  5. Troubleshooting
    1. Resolving DMP issues
      1.  
        When a DMP license is no longer valid
      2.  
        When an unknown disk group appears in a DMP environment
    2. Using status information
      1.  
        Path status
      2.  
        Path states
  6. Glossary
    1.  
      Dynamic Multi-Pathing glossary

How DMP monitors I/O on paths

DMP works in close coordination with the Windows MPIO framework to participate in the I/O processing and monitoring. DMP performs various operations such as error handling, path verification/failover, SCSI reservation/release, and statistics collection.

In case of an I/O error on a path, DMP determines if the I/O should be retried after a certain interval on the same path or the path should be invalidated for further I/O processing. It then decides which alternate path should be picked up for I/O in case of a fatal error on the previous path.

DMP performs path verification every 30 seconds (Default) for all the paths to determine their health for I/O processing and resume I/O on the paths that have been restored. Path verification helps in selecting healthy paths in case a path is reporting intermittent failures.

DMP gathers I/O statistics on each path. The vxdmpadm iostat command can be used to provide information about the I/O statistics for a single disk or for all the disks in an array. The statistics can be displayed after a specified number of seconds and for a specified number of times. Alternately, the VEA GUI also shows the number of Read/Write operations that have occurred through the paths.