Administering Solaris I/O Multipathing

You determine and configure Solaris OS multipathing support by using mpathadm commands. The mpathadm command enables multipathing administration through the ANSI standard Multipath Management API. The terms used in this chapter to denote a path, initiator port, target port, and LU are consistent with the T10 specification.

Perform the following tasks to administer multipathing devices.

Displaying Multipathing Support Information
Configuring Automatic Failback for Multipathing Support

Displaying Multipathing Support Information

You can use the mpathadm command to display multipathing support information and also manage multipathing discovery. Multipathing support and property information is identified with the Multipath Management API plug-in library name, which is displayed by using the mpathadm command.

How to Display Multipathing Support Information

Become superuser.

Identify the multipathing support on your system.

# mpathadm list mpath-support
mpath-support: libmpscsi_vhci.so

Display the multipathing support properties for a specified mpath support name.

# mpathadm show mpath-support libmpscsi_vhci.so
mpath-support:  libmpscsi_vhci.so
        Vendor:  Sun Microsystems
        Driver Name:  scsi_vhci
        Default Load Balance:  round-robin
        Supported Load Balance Types:  
                round-robin
                logical-block
        Allows To Activate Target Port Group Access:  yes
        Allows Path Override:  no
        Supported Auto Failback Config:  yes
        Auto Failback:  on
        Failback Polling Rate (current/max):  0/0
        Supported Auto Probing Config:  0
        Auto Probing:  NA
        Probing Polling Rate (current/max):  NA/NA
        Supported Devices:
                Vendor:  SUN     
                Product:  T300            
                Revision:  
                Supported Load Balance Types:
                        round-robin

                Vendor:  SUN     
                Product:  T4              
                Revision:  
                Supported Load Balance Types:
                        round-robin
.
.
.

The command output also shows a list of device products that is supported by the multipathing support software. The multipathing support libmpscsi_vhci.so library file supports T10 target port group compliant devices by default.

How to Display Properties of a Specific Initiator Port

The following steps describe how to display the properties of an initiator port.

List the initiator ports.

# mpathadm list initiator-port
Initiator Port:  iqn.1986-03.com.sun:01:ffffffffffff.4e94f9bd,4000002a00ff
Initiator Port:  210100e08ba41feb
Initiator Port:  210000e08b841feb

Display the specific initiator port's properties.

# mpathadm show initiator-port 2000000173018713
Initiator Port:  210100e08ba41feb
        Transport Type:  Fibre Channel
        OS Device File:  /devices/pci@1,0/pci1022,7450@1/pci1077,141@2,1/fp@0,0

How to Display Specific LU Information

Display the list of LUs, along with the properties for each LUN by using the mpathadm command. The displayed list of LUs contain names that in turn can be used to display the properties of a particular LU.

Display a list of multipathed LUs.

# mpathadm list lu
        /dev/rdsk/c0t600144F08069703400004E828EE10004d0s2
                Total Path Count: 8
                Operational Path Count: 8
        /dev/rdsk/c0t600144F08069703400004E8183DF0002d0s2
                Total Path Count: 8
                Operational Path Count: 8
        /dev/rdsk/c0t600A0B800026D63A0000A4994E2342D4d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800029065C00007CF54E234013d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800029065C00007CF44E233FCFd0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800026D63A0000A4974E23424Ed0s2
                Total Path Count: 4
                Operational Path Count: 4
.
.
.

Display configuration information about a specific LU using the LU name from the list.

# mpathadm show lu /dev/rdsk/c4t60003BA27D2120004204AC2B000DAB00d0s2
        mpath-support:  libmpscsi_vhci.so
        Vendor:  SUN     
        Product:  Sun Storage NAS
        Revision:  1.0 
        Name Type:  unknown type
        Name:  600144f08069703400004e828ee10004
        Asymmetric:  yes
        Current Load Balance:  round-robin
        Logical Unit Group ID:  NA
        Auto Failback:  on
        Auto Probing:  NA

        Paths:  
                Initiator Port Name:  210100e08ba41feb
                Target Port Name:  2100001b329b6c3f
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210100e08ba41feb
                Target Port Name:  2101001b32bb6c3f
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210100e08ba41feb
                Target Port Name:  2100001b329b793c
                Override Path:  NA
                Path State:  OK
                Disabled:  no
.
.
.

        Target Port Groups:  
                ID:  0
                Explicit Failover:  no
                Access State:  active optimized
                Target Ports:
                        Name:  2100001b329b6c3f
                        Relative ID:  1

                        Name:  2101001b32bb6c3f
                        Relative ID:  2

                ID:  1
                Explicit Failover:  no
                Access State:  standby
                Target Ports:
                        Name:  2100001b329b793c
                        Relative ID:  257

                        Name:  2101001b32bb793c
                        Relative ID:  256

How to Display All LUs Associated With a Specific Target Port

Use the steps below to display paths through a target port.

Display a list of LUs.

# mpathadm list lu
       /dev/rdsk/c0t600144F08069703400004E828EE10004d0s2
                Total Path Count: 8
                Operational Path Count: 8
        /dev/rdsk/c0t600144F08069703400004E8183DF0002d0s2
                Total Path Count: 8
                Operational Path Count: 8
        /dev/rdsk/c0t600A0B800026D63A0000A4994E2342D4d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800029065C00007CF54E234013d0s2
                Total Path Count: 4
                Operational Path Count: 4
.
.
.

Display specific LU information to determine the target ports.

# mpathadm show lu /dev/rdsk/c0t600A0B800029065C00007CF54E234013d0s2
Logical Unit:  /dev/rdsk/c0t600A0B800029065C00007CF54E234013d0s2
        mpath-support:  libmpscsi_vhci.so
        Vendor:  SUN     
        Product:  CSM200_R        
        Revision:  0660
        Name Type:  unknown type
        Name:  600a0b800029065c00007cf54e234013
        Asymmetric:  yes
        Current Load Balance:  round-robin
        Logical Unit Group ID:  NA
        Auto Failback:  on
        Auto Probing:  NA

        Paths:  
                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200800a0b826d63b
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200900a0b826d63b
                Override Path:  NA
                Path State:  OK
                Disabled:  no
.
.
.

        Target Port Groups:  
                ID:  4
                Explicit Failover:  yes
                Access State:  standby
                Target Ports:
                        Name:  200800a0b826d63b
                        Relative ID:  0

                        Name:  200800a0b826d63c
                        Relative ID:  0

                ID:  14
                Explicit Failover:  yes
                Access State:  active
                Target Ports:
                        Name:  200900a0b826d63b
                        Relative ID:  0

                        Name:  200900a0b826d63c
                        Relative ID:  0

Display the specific target port information.

# mpathadm list lu -t 20030003ba27d212
mpath-support:  libmpscsi_vhci.so
        /dev/rdsk/c0t600A0B800026D63A0000A4994E2342D4d0s2
                Total Path Count: 4
                Operational Path Count: 4
mpath-support:  libmpscsi_vhci.so
        /dev/rdsk/c0t600A0B800029065C00007CF54E234013d0s2
                Total Path Count: 4
                Operational Path Count: 4
mpath-support:  libmpscsi_vhci.so
        /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2
                Total Path Count: 4
                Operational Path Count: 4
mpath-support:  libmpscsi_vhci.so
        /dev/rdsk/c0t600A0B800029065C00007CF44E233FCFd0s2
                Total Path Count: 4
                Operational Path Count: 4
.
.
.

How to Display a LU With a Specific Name

Display detailed information on multipathed LUs, including path and target port group information. Note that the name property in the information represents the identifier for this LU, derived from the hardware, and used by this system. If the name is derived from SCSI Inquiry Vital Product Data (VPD) page 83h, the name type property represents an associated identifier type defined by the SCSI standards.

Display a list of multipathed LUs.

# mpathadm list lu
        /dev/rdsk/c0t600144F08069703400004E828EE10004d0s2
                Total Path Count: 8
                Operational Path Count: 8
        /dev/rdsk/c0t600144F08069703400004E8183DF0002d0s2
                Total Path Count: 8
                Operational Path Count: 8
        /dev/rdsk/c0t600A0B800026D63A0000A4994E2342D4d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800029065C00007CF54E234013d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800029065C00007CF44E233FCFd0s2
                Total Path Count: 4
                Operational Path Count: 4
.
.
.

Display a selected LU's configuration information.

# mpathadm show lu /dev/rdsk/c0t600A0B800026D63A0000A4994E2342D4d0s2
Logical Unit:  /dev/rdsk/c0t600A0B800026D63A0000A4994E2342D4d0s2
        mpath-support:  libmpscsi_vhci.so
        Vendor:  SUN     
        Product:  CSM200_R        
        Revision:  0660
        Name Type:  unknown type
        Name:  600a0b800026d63a0000a4994e2342d4
        Asymmetric:  yes
        Current Load Balance:  round-robin
        Logical Unit Group ID:  NA
        Auto Failback:  on
        Auto Probing:  NA

        Paths:  
                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200800a0b826d63b
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200900a0b826d63b
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200800a0b826d63c
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200900a0b826d63c
                Override Path:  NA
                Path State:  OK
                Disabled:  no

        Target Port Groups:  
                ID:  3
                Explicit Failover:  yes
                Access State:  active
                Target Ports:
                        Name:  200800a0b826d63b
                        Relative ID:  0

                        Name:  200800a0b826d63c
                        Relative ID:  0

                ID:  13
                Explicit Failover:  yes
                Access State:  standby
                Target Ports:
                        Name:  200900a0b826d63b
                        Relative ID:  0

                        Name:  200900a0b826d63c
                        Relative ID:  0

Display the selected LU information.

# mpathadm list lu -n 600a0b800026d63a0000a4994e2342d4
mpath-support:  libmpscsi_vhci.so
        /dev/rdsk/c0t600A0B800026D63A0000A4994E2342D4d0s2
                Total Path Count: 4
                Operational Path Count: 4

Configuring Automatic Failback for Multipathing Support

Symmetrical devices can provide automatic failback to a possible optimal path. If a failover occurs on the initial path, the standby path becomes the new online path. Usually the standby path is a suboptimal path. When automatic failback is enabled, the initial path comes back online and failover to the initial path automatically occurs.

How to Configure Automatic Failback for Specific Multipathing Support

Become superuser.

Display the supported multipath driver information.

# mpathadm list mpath-support
mpath-support: libmpscsi_vhci.so

Enable automatic failback support for the supported multipath driver.
```
# mpathadm modify mpath-support -a on libmpscsi_vhci.so
 
```

Confirm the configuration change.

# mpathadm show mpath-support libmpscsi_vhci.so
mpath-support:  libmpscsi_vhci.so
        Vendor:  Sun Microsystems
        Driver Name:  scsi_vhci
        Default Load Balance:  round-robin
        Supported Load Balance Types:  
                round-robin
                logical-block
        Allows To Activate Target Port Group Access:  yes
        Allows Path Override:  no
        Supported Auto Failback Config:  1
        Auto Failback:  on
        Failback Polling Rate (current/max):  0/0
        Supported Auto Probing Config:  0
        Auto Probing:  NA
        Probing Polling Rate (current/max):  NA/NA
        Supported Devices:
                Vendor:  SUN     
                Product:  T300            
                Revision:  
                Supported Load Balance Types:
                        round-robin

                Vendor:  SUN     
                Product:  T4              
                Revision:  
                Supported Load Balance Types:
                        round-robin
.
.
.

Note - The automatic display initiated by the mpathadm modify command setting is effective while the system is running. However, to keep the changed setting persistent, you must update the /kernel/drv/scsi_vhci.conf file. Refer to Configuring Automatic Failback.

How to Fail Over a LU

This operation is applicable only to devices in the following two categories:

Asymmetric devices with a proprietary failover mechanism recognized and supported by multipathing support
Devices conforming to the T10 Standard Target Port Group Support libmpscsi_vhci.so and providing explicit mode asymmetric LU access

Display a list of multipathed LUs.

# mpathadm list lu
        /dev/rdsk/c0t600144F08069703400004E828EE10004d0s2
                Total Path Count: 8
                Operational Path Count: 8
        /dev/rdsk/c0t600144F08069703400004E8183DF0002d0s2
                Total Path Count: 8
                Operational Path Count: 8
        /dev/rdsk/c0t600A0B800026D63A0000A4994E2342D4d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800029065C00007CF54E234013d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2
                Total Path Count: 4
                Operational Path Count: 4
.
.
.

Display a specific LU's configuration information.

# mpathadm show lu /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2
Logical Unit:  /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2
        mpath-support:  libmpscsi_vhci.so
        Vendor:  SUN     
        Product:  CSM200_R        
        Revision:  0660
        Name Type:  unknown type
        Name:  600a0b800026d63a0000a4984e234298
        Asymmetric:  yes
        Current Load Balance:  round-robin
        Logical Unit Group ID:  NA
        Auto Failback:  on
        Auto Probing:  NA

        Paths:  
                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200800a0b826d63b
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200900a0b826d63b
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200800a0b826d63c
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200900a0b826d63c
                Override Path:  NA
                Path State:  OK
                Disabled:  no

        Target Port Groups:  
                ID:  5
                Explicit Failover:  yes
                Access State:  active
                Target Ports:
                        Name:  200800a0b826d63b
                        Relative ID:  0

                        Name:  200800a0b826d63c
                        Relative ID:  0

                ID:  15
                Explicit Failover:  yes
                Access State:  standby
                Target Ports:
                        Name:  200900a0b826d63b
                        Relative ID:  0

                        Name:  200900a0b826d63c
                        Relative ID:  0

Manually force a LU failover.
```
# mpathadm failover lu /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2
```
If this operation is successful, the access state of the device's target port groups changes as a result of the logical unit failover.

Confirm the access state change.

# mpathadm show lu /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2
Logical Unit:  /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2
        mpath-support:  libmpscsi_vhci.so
        Vendor:  SUN     
        Product:  CSM200_R        
        Revision:  0660
        Name Type:  unknown type
        Name:  600a0b800026d63a0000a4984e234298
        Asymmetric:  yes
        Current Load Balance:  round-robin
        Logical Unit Group ID:  NA
        Auto Failback:  on
        Auto Probing:  NA

        Paths:  
                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200800a0b826d63b
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200900a0b826d63b
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200800a0b826d63c
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200900a0b826d63c
                Override Path:  NA
                Path State:  OK
                Disabled:  no

        Target Port Groups:  
                ID:  5
                Explicit Failover:  yes
                Access State:  standby
                Target Ports:
                        Name:  200800a0b826d63b
                        Relative ID:  0

                        Name:  200800a0b826d63c
                        Relative ID:  0

                ID:  15
                Explicit Failover:  yes
                Access State:  active
                Target Ports:
                        Name:  200900a0b826d63b
                        Relative ID:  0

                        Name:  200900a0b826d63c
                        Relative ID:  0

How to Enable a LU Path

If the path to a LU is disabled, the enable command changes the path back to enabled. The full path must be specified using the initiator port name, target port name, and the LU. To verify the change, run the show command for the logical unit.

Display a list of multipathed LUs.

# mpathadm list lu
        /dev/rdsk/c0t600144F08069703400004E828EE10004d0s2
                Total Path Count: 8
                Operational Path Count: 8
        /dev/rdsk/c0t600144F08069703400004E8183DF0002d0s2
                Total Path Count: 8
                Operational Path Count: 8
        /dev/rdsk/c0t600A0B800026D63A0000A4994E2342D4d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800029065C00007CF54E234013d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800029065C00007CF44E233FCFd0s2
                Total Path Count: 4
                Operational Path Count: 4
.
.
.

Display the selected LU's configuration information.

# mpathadm show lu 
Logical Unit:  /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2
        mpath-support:  libmpscsi_vhci.so
        Vendor:  SUN     
        Product:  CSM200_R        
        Revision:  0660
        Name Type:  unknown type
        Name:  600a0b800026d63a0000a4984e234298
        Asymmetric:  yes
        Current Load Balance:  round-robin
        Logical Unit Group ID:  NA
        Auto Failback:  on
        Auto Probing:  NA

        Paths:  
                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200800a0b826d63b
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200900a0b826d63b
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200800a0b826d63c
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200900a0b826d63c
                Override Path:  NA
                Path State:  OK
                Disabled:  no

        Target Port Groups:  
                ID:  5
                Explicit Failover:  yes
                Access State:  standby
                Target Ports:
                        Name:  200800a0b826d63b
                        Relative ID:  0

                        Name:  200800a0b826d63c
                        Relative ID:  0

                ID:  15
                Explicit Failover:  yes
                Access State:  active
                Target Ports:
                        Name:  200900a0b826d63b
                        Relative ID:  0

                        Name:  200900a0b826d63c
                        Relative ID:  0

Enable the LU path.

# mpathadm enable path -i 210000e08b841feb -t 200900a0b826d63b \ 
           -l /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2

How to Disable a LU Path

This operation makes the path unavailable for the LU, regardless of its operational state.

Note - The disabled state is not persistent across rebooting. If the path is operational before the next boot sequence, it is enabled by default. This operation is not allowed when the given path is the last operational path remaining.

Display a list of multipathed LUs.

# mpathadm list lu
        /dev/rdsk/c0t600144F08069703400004E828EE10004d0s2
                Total Path Count: 8
                Operational Path Count: 8
        /dev/rdsk/c0t600144F08069703400004E8183DF0002d0s2
                Total Path Count: 8
                Operational Path Count: 8
        /dev/rdsk/c0t600A0B800026D63A0000A4994E2342D4d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800029065C00007CF54E234013d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800026D63A0000A4984E234298d0s2
                Total Path Count: 4
                Operational Path Count: 4
        /dev/rdsk/c0t600A0B800029065C00007CF44E233FCFd0s2
                Total Path Count: 4
                Operational Path Count: 4
.
.
.

Display the specific LU's configuration information.

# mpathadm show lu /dev/rdsk/c0t600A0B800029065C00007CF34E233F89d0s2
Logical Unit:  /dev/rdsk/c0t600A0B800029065C00007CF34E233F89d0s2
        mpath-support:  libmpscsi_vhci.so
        Vendor:  SUN     
        Product:  CSM200_R        
        Revision:  0660
        Name Type:  unknown type
        Name:  600a0b800029065c00007cf34e233f89
        Asymmetric:  yes
        Current Load Balance:  round-robin
        Logical Unit Group ID:  NA
        Auto Failback:  on
        Auto Probing:  NA

        Paths:  
                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200800a0b826d63b
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200900a0b826d63b
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200800a0b826d63c
                Override Path:  NA
                Path State:  OK
                Disabled:  no

                Initiator Port Name:  210000e08b841feb
                Target Port Name:  200900a0b826d63c
                Override Path:  NA
                Path State:  OK
                Disabled:  no

        Target Port Groups:  
                ID:  8
                Explicit Failover:  yes
                Access State:  standby
                Target Ports:
                        Name:  200800a0b826d63b
                        Relative ID:  0

                        Name:  200800a0b826d63c
                        Relative ID:  0

                ID:  18
                Explicit Failover:  yes
                Access State:  active
                Target Ports:
                        Name:  200900a0b826d63b
                        Relative ID:  0

                        Name:  200900a0b826d63c
                        Relative ID:  0

Select an initiator port and a target port name.

Disable the selected LU path.

# mpathadm disable path -i 210000e08b841feb -t 200900a0b826d63b \
           -l /dev/rdsk/c0t600A0B800029065C00007CF34E233F89d0s2

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	Oracle Solaris SAN Configuration and Multipathing Guide Oracle Solaris 10 1/13 Information Library