Dynamic Multi-Pathing 7.3.1 Administrator's Guide - Linux

Last Published:
Product(s): InfoScale & Storage Foundation (7.3.1)
  1. Understanding DMP
    1.  
      About Dynamic Multi-Pathing (DMP)
    2. How DMP works
      1. How DMP monitors I/O on paths
        1.  
          Path failover mechanism
        2.  
          Subpaths Failover Group (SFG)
        3.  
          Low Impact Path Probing (LIPP)
        4.  
          I/O throttling
      2.  
        Load balancing
      3. DMP in a clustered environment
        1.  
          About enabling or disabling controllers with shared disk groups
    3.  
      Multi-controller ALUA support
    4.  
      Multiple paths to disk arrays
    5.  
      Device discovery
    6.  
      Disk devices
    7. Disk device naming in DMP
      1.  
        About operating system-based naming
      2. About enclosure-based naming
        1.  
          Summary of enclosure-based naming
        2.  
          Enclosure based naming with the Array Volume Identifier (AVID) attribute
  2. Setting up DMP to manage native devices
    1.  
      About setting up DMP to manage native devices
    2.  
      Displaying the native multi-pathing configuration
    3.  
      Migrating LVM volume groups to DMP
    4.  
      Migrating to DMP from EMC PowerPath
    5.  
      Migrating to DMP from Hitachi Data Link Manager (HDLM)
    6.  
      Migrating to DMP from Linux Device Mapper Multipath
    7. Using Dynamic Multi-Pathing (DMP) devices with Oracle Automatic Storage Management (ASM)
      1.  
        Enabling Dynamic Multi-Pathing (DMP) devices for use with Oracle Automatic Storage Management (ASM)
      2.  
        Removing Dynamic Multi-Pathing (DMP) devices from the listing of Oracle Automatic Storage Management (ASM) disks
      3.  
        Migrating Oracle Automatic Storage Management (ASM) disk groups on operating system devices to Dynamic Multi-Pathing (DMP) devices
    8.  
      Adding DMP devices to an existing LVM volume group or creating a new LVM volume group
    9.  
      Removing DMP support for native devices
  3. Administering DMP
    1.  
      About enabling and disabling I/O for controllers and storage processors
    2.  
      About displaying DMP database information
    3.  
      Displaying the paths to a disk
    4.  
      Setting customized names for DMP nodes
    5. Administering DMP using the vxdmpadm utility
      1.  
        Retrieving information about a DMP node
      2.  
        Displaying consolidated information about the DMP nodes
      3.  
        Displaying the members of a LUN group
      4.  
        Displaying paths controlled by a DMP node, controller, enclosure, or array port
      5.  
        Displaying information about controllers
      6.  
        Displaying information about enclosures
      7.  
        Displaying information about array ports
      8.  
        User-friendly CLI outputs for ALUA arrays
      9.  
        Displaying information about devices controlled by third-party drivers
      10.  
        Displaying extended device attributes
      11.  
        Suppressing or including devices from VxVM control
      12. Gathering and displaying I/O statistics
        1.  
          Displaying cumulative I/O statistics
        2.  
          Displaying statistics for queued or erroneous I/Os
        3.  
          Examples of using the vxdmpadm iostat command
      13.  
        Setting the attributes of the paths to an enclosure
      14.  
        Displaying the redundancy level of a device or enclosure
      15.  
        Specifying the minimum number of active paths
      16.  
        Displaying the I/O policy
      17. Specifying the I/O policy
        1.  
          Scheduling I/O on the paths of an Asymmetric Active/Active or an ALUA array
        2.  
          Example of applying load balancing in a SAN
      18.  
        Disabling I/O for paths, controllers, array ports, or DMP nodes
      19.  
        Enabling I/O for paths, controllers, array ports, or DMP nodes
      20.  
        Renaming an enclosure
      21.  
        Configuring the response to I/O failures
      22.  
        Configuring the I/O throttling mechanism
      23.  
        Configuring Subpaths Failover Groups (SFG)
      24.  
        Configuring Low Impact Path Probing (LIPP)
      25.  
        Displaying recovery option values
      26.  
        Configuring DMP path restoration policies
      27.  
        Stopping the DMP path restoration thread
      28.  
        Displaying the status of the DMP path restoration thread
      29.  
        Configuring Array Policy Modules
  4. Administering disks
    1.  
      About disk management
    2. Discovering and configuring newly added disk devices
      1.  
        Partial device discovery
      2. About discovering disks and dynamically adding disk arrays
        1.  
          How DMP claims devices
        2.  
          Disk categories
        3.  
          Adding DMP support for a new disk array
        4.  
          Enabling discovery of new disk arrays
      3.  
        About third-party driver coexistence
      4. How to administer the Device Discovery Layer
        1.  
          Listing all the devices including iSCSI
        2.  
          Listing all the Host Bus Adapters including iSCSI
        3.  
          Listing the ports configured on a Host Bus Adapter
        4.  
          Listing the targets configured from a Host Bus Adapter or a port
        5.  
          Listing the devices configured from a Host Bus Adapter and target
        6.  
          Getting or setting the iSCSI operational parameters
        7.  
          Listing all supported disk arrays
        8.  
          Excluding support for a disk array library
        9.  
          Re-including support for an excluded disk array library
        10.  
          Listing excluded disk arrays
        11.  
          Listing disks claimed in the DISKS category
        12.  
          Displaying details about an Array Support Library
        13.  
          Adding unsupported disk arrays to the DISKS category
        14.  
          Removing disks from the DISKS category
        15.  
          Foreign devices
    3. Changing the disk device naming scheme
      1.  
        Displaying the disk-naming scheme
      2.  
        Regenerating persistent device names
      3.  
        Changing device naming for enclosures controlled by third-party drivers
    4.  
      Discovering the association between enclosure-based disk names and OS-based disk names
  5. Dynamic Reconfiguration of devices
    1.  
      About online Dynamic Reconfiguration
    2. Reconfiguring a LUN online that is under DMP control using the Dynamic Reconfiguration tool
      1.  
        Removing LUNs dynamically from an existing target ID
      2.  
        Adding new LUNs dynamically to a target ID
      3.  
        Replacing LUNs dynamically from an existing target ID
      4.  
        Replacing a host bus adapter online
    3. Manually reconfiguring a LUN online that is under DMP control
      1.  
        Overview of manually reconfiguring a LUN
      2.  
        Manually removing LUNs dynamically from an existing target ID
      3.  
        Manually adding new LUNs dynamically to a new target ID
      4.  
        About detecting target ID reuse if the operating system device tree is not cleaned up
      5.  
        Scanning an operating system device tree after adding or removing LUNs
      6.  
        Manually cleaning up the operating system device tree after removing LUNs
    4.  
      Changing the characteristics of a LUN from the array side
    5.  
      Upgrading the array controller firmware online
    6.  
      Reformatting NVMe devices manually
  6. Event monitoring
    1.  
      About the Dynamic Multi-Pathing (DMP) event source daemon (vxesd)
    2.  
      Fabric Monitoring and proactive error detection
    3.  
      Dynamic Multi-Pathing (DMP) discovery of iSCSI and SAN Fibre Channel topology
    4.  
      DMP event logging
    5.  
      Starting and stopping the Dynamic Multi-Pathing (DMP) event source daemon
  7. Performance monitoring and tuning
    1.  
      About tuning Dynamic Multi-Pathing (DMP) with templates
    2.  
      DMP tuning templates
    3.  
      Example DMP tuning template
    4.  
      Tuning a DMP host with a configuration attribute template
    5.  
      Managing the DMP configuration files
    6.  
      Resetting the DMP tunable parameters and attributes to the default values
    7.  
      DMP tunable parameters and attributes that are supported for templates
    8.  
      DMP tunable parameters
  8. Appendix A. DMP troubleshooting
    1.  
      Recovering from errors when you exclude or include paths to DMP
    2.  
      Downgrading the array support
  9. Appendix B. Reference
    1.  
      Command completion for Veritas commands

Displaying paths controlled by a DMP node, controller, enclosure, or array port

The vxdmpadm getsubpaths command lists all of the paths known to Dynamic Multi-Pathing (DMP). The vxdmpadm getsubpaths command also provides options to list the subpaths through a particular DMP node, controller, enclosure, or array port. To list the paths through an array port, specify either a combination of enclosure name and array port id, or array port worldwide name (WWN).

To list all subpaths known to DMP:

# vxdmpadm getsubpaths
NAME   STATE[A]   PATH-TYPE[M]         DMPNODENAME       ENCLR-NAME   CTLR   ATTRS
=============================================================================
sdaf   ENABLED(A) PRIMARY              ams_wms0_130      ams_wms0      c2       -
sdc    ENABLED    SECONDARY            ams_wms0_130      ams_wms0      c3       -
sdb    ENABLED(A)   -                  vm04_disk_24      disk          c0       -
sda    ENABLED(A)   -                  vm04_disk_25      disk          c0       -
sdaa   ENABLED    Active/Non-Optimized emc_clariion0_438 emc_clariion0 c1       -
sdak   ENABLED(A) Active/Optimized(P)  emc_clariion0_438 emc_clariion0 c6       -

The vxdmpadm getsubpaths command combined with the dmpnodename attribute displays all the paths to a LUN that are controlled by the specified DMP node name from the /dev/vx/dmp directory:

# vxdmpadm getsubpaths dmpnodename=sdby

NAME   STATE[A]   PATH-TYPE[M] CTLR-NAME  ENCLR-TYPE  ENCLR-NAME  ATTRS   PRIORITY
==================================================================================
sdbp   ENABLED      -          c1          EMC        emc0          -       -
sdbs   ENABLED      -          c1          EMC        emc0          -       -
sdbv   ENABLED      -          c6          EMC        emc0          -       -
sdby   ENABLED(A)   -          c6          EMC        emc0          -       -

For A/A arrays, all enabled paths that are available for I/O are shown as ENABLED(A).

For A/P arrays in which the I/O policy is set to singleactive, only one path is shown as ENABLED(A). The other paths are enabled but not available for I/O. If the I/O policy is not set to singleactive, DMP can use a group of paths (all primary or all secondary) for I/O, which are shown as ENABLED(A).

Paths that are in the DISABLED state are not available for I/O operations.

A path that was manually disabled by the system administrator displays as DISABLED(M). A path that failed displays as DISABLED.

You can use getsubpaths to obtain information about all the paths that are connected to a particular HBA controller:

# vxdmpadm getsubpaths ctlr=c1

NAME STATE[A]   PATH-TYPE[M]         DMPNODENAME        ENCLR-TYPE   ENCLR-NAME     ATTRS  PRIORITY
===================================================================================================
sdh  ENABLED    Active/Non-Optimized emc_clariion0_429  EMC_CLARiiON  emc_clariion0     -       -
sdr  ENABLED(A) Active/Optimized(P)  emc_clariion0_429  EMC_CLARiiON  emc_clariion0     -       -
sdm  ENABLED(A) Active/Optimized(P)  emc_clariion0_430  EMC_CLARiiON  emc_clariion0     -       -
sdw  ENABLED    Active/Non-Optimized emc_clariion0_430  EMC_CLARiiON  emc_clariion0     -       -

You can also use getsubpaths to obtain information about all the paths that are connected to a port on an array. The array port can be specified by the name of the enclosure and the array port ID, or by the WWN identifier of the array port:

# vxdmpadm getsubpaths enclosure=enclosure portid=portid
# vxdmpadm getsubpaths pwwn=pwwn

For example, to list subpaths through an array port through the enclosure and the array port ID:

# vxdmpadm getsubpaths enclosure=emc_clariion0 portid=A7
NAME STATE[A]   PATH-TYPE[M]         DMPNODENAME       ENCLR-NAME   CTLR ATTRS PRIORITY
=======================================================================================
sdal ENABLED(A) Active/Optimized     emc_clariion0_429 emc_clariion0 c6   -      -
sdr  ENABLED(A) Active/Optimized     emc_clariion0_429 emc_clariion0 c1   -      -
sdaq ENABLED    Active/Non-Optimized emc_clariion0_430 emc_clariion0 c6   -      -
sdw  ENABLED    Active/Non-Optimized emc_clariion0_430 emc_clariion0 c1   -      -

For example, to list subpaths through an array port through the WWN:

# vxdmpadm getsubpaths pwwn=50:06:01:67:3e:a0:75:95
NAME STATE[A]   PATH-TYPE[M]         CTLR-NAME ENCLR-TYPE   ENCLR-NAME     ATTRS PRIORITY
=========================================================================================
sdal ENABLED(A) Active/Optimized     c6        EMC_CLARiiON  emc_clariion0  -       -
sdr  ENABLED(A) Active/Optimized(P)  c1        EMC_CLARiiON  emc_clariion0  -       -
sdaq ENABLED    Active/Non-Optimized c6        EMC_CLARiiON  emc_clariion0  -       -
sdw  ENABLED    Active/Non-Optimized c1        EMC_CLARiiON  emc_clariion0  -       -
# vxdmpadm getsubpaths pwwn=20:00:00:E0:8B:06:5F:19

You can use getsubpaths to obtain information about all the subpaths of an enclosure.

# vxdmpadm getsubpaths enclosure=enclosure_name [ctlr=ctlrname]

To list all subpaths of an enclosure:

# vxdmpadm getsubpaths enclosure=emc_clariion0	
NAME         STATE[A]   PATH-TYPE[M] DMPNODENAME  ENCLR-NAME   CTLR    ATTRS
================================================================================
sdav         ENABLED(A) PRIMARY      emc_clariion0_1017 emc_clariion0 c3    -
sdbf         ENABLED    SECONDARY    emc_clariion0_1017 emc_clariion0 c3    -
sdau         ENABLED(A) PRIMARY      emc_clariion0_1018 emc_clariion0 c3    -
sdbe         ENABLED    SECONDARY    emc_clariion0_1018 emc_clariion0 c3    -

To list all subpaths of a controller on an enclosure:

# vxdmpadm getsubpaths enclosure=emc_clariion0

By default, the output of the vxdmpadm getsubpaths command is sorted by enclosure name, DMP node name, and within that, path name.

To sort the output based on the pathname, the DMP node name, the enclosure name, or the host controller name, use the -s option.

To sort subpaths information, use the following command:

# vxdmpadm -s {path | dmpnode | enclosure | ctlr} getsubpaths \
[all | ctlr=ctlr_name | dmpnodename=dmp_device_name | \
enclosure=enclr_name [ctlr=ctlr_name | portid=array_port_ID] | \
pwwn=port_WWN | tpdnodename=tpd_node_name] 

See Setting customized names for DMP nodes.