How to Disable HP-UX 11iv3 Native Multi-Pathing ALUA mode for Storage Foundation 5.0 and 5.0.1.

On  Storage  Foundation  5.0 and 5.0.1,  HP-UX 11iv3  and for the Storage  Arrays  operating in
ALUA  ( Asymmetric Logic Unit Access ) mode , Native  Multi-Pathing  ALUA mode is
required to be disabled to ensure proper functioning of the DMP in Storage Foundation
stack.

NOTE : This procedure must not be performed if deploying EMC Powerpath.

 

This can be done in 2 ways .
1.disabling Native Multi-Pathing ALUA (nMP) mode at LUN Level
2.disabling Native Multi-Pathing ALUA (nMP ) mode at "esdisk" driver level.
 

Procedures for either methods are shown below with examples

 

1. Disabling Native Multi-Pathing ALUA (nMP) mode at LUN level.
 

If this method is used , the "alua_enabled" attribute for each LUN and its multiple paths
is set to "false".

Additionally this attribute "alua_enabled" must be made persistent by setting "save_attr"

The scsimgr (1M) command is used to enable/disable ALUA mode for a LUN

a ) Determine if the attribute has been already set to disabled, i.e.  alua_enabled = false.

The below command shows the options in scsimgr to display the alua_enabled attribute
and its persistence.

  #  scsimgr get_attr -D  /dev/rdisk/disk460 -a alua_enabled

          SCSI ATTRIBUTES FOR LUN : /dev/rdisk/disk460

          name = alua_enabled
          current = true
          default = true
          saved =

b ) To disable nMP  ALUA for a LUN  , set  the attribute alua_enabled = 0 using scsimgr
    command.

   #  scsimgr set_attr -D  /dev/rdisk/disk460 -a alua_enabled=0

      Value of attribute alua_enabled set successfully

c ) To verify that the attribute is set correctly please run the below scsimgr command again.

   #  scsimgr get_attr -D  /dev/rdisk/disk460 -a alua_enabled

 
       SCSI ATTRIBUTES FOR LUN : /dev/rdisk/disk460

       name = alua_enabled
       current = false
       default = true
       saved =

NOTE : In above output current state has been changed to "false" indicating the native ALUA
           attribute for this particular LUN path has been disabled.

d ) To make this attribute persistent  across  host reboots   by using in the "save_attr"
    option in  scsimgr command

         #  scsimgr save_attr -D /dev/rdisk/disk460 -a alua_enabled=0

            Value of attribute alua_enabled set successfully

NOTE : Host Reboot is not required to make these changes effective . It is recommended not to run i/o when making these changes.

e ) Validate that both the attributes "name" and  "saved" are set correctly.

          # scsimgr get_attr -D  /dev/rdisk/disk460 -a alua_enabled

            SCSI ATTRIBUTES FOR LUN : /dev/rdisk/disk460

            name = alua_enabled
            current = false
            default = true
            saved = false

f )     To display the "alua_enabled" attribute for all LUNs in a server

          #  scsimgr -p get_attr all_lun -a device_file -a alua_enabled

 

Note:The above mentioned steps should be executed for all agile DSFs in /dev/rdisk/ directory.
 

If new lun(s)/dsf(s)  are  added to the host  at  runtime  on the HP-UX host ( SF is already
 

configured and then new LUN(s) are added), then  the above mentioned steps need to executed
 

separately for the newly added LUN(s).
 

       

2.  Disabling nMP ALUA at "esdisk" driver level.


This will set the attribute "alua_enabled"  at the "esdisk" driver level thereby disabling/enabling
ALUA ,based on attribute value,for all LUN bound to "esdisk" driver.

The following example shows how to set, save  and display current and default setting for
"alua_enabled"  attribute and also disabling the ALUA persistently  at the driver level.



a)     To disable ALUA at esdisk driver run following command.

           # scsimgr  set_attr -N  "/escsi/esdisk" -a alua_enabled = 0

             Value of attribute alua_enabled set successfully


 

b)    To make this attribute persistent across host reboots save it using below command.
 

          #   scsimgr save_attr -N "/escsi/esdisk" -a alua_enabled=0

              Value of attribute alua_enabled saved successfully

NOTE : Host Reboot is not required to make these changes effective . It is recommended not to run i/o when making these changes.



c)    To check or display the attribute changes use get_attr as in the example below.

          #  scsimgr get_attr -N "/escsi/esdisk" -a alua_enabled

         SCSI ATTRIBUTES FOR SETTABLE ATTRIBUTE SCOPE : "/escsi/esdisk"

                 name = alua_enabled
                 current = false
                 default = true
                 saved = false

d)     To check the "alua_enable" attributes for  disk460 e.g.

          #   scsimgr get_attr -D /dev/rdisk/disk460 -a alua_enabled

         SCSI ATTRIBUTES FOR LUN : /dev/rdisk/disk460

                 name = alua_enabled
                 current = false
                 default = false
                 saved =


Please refer to scsimgr(1M) manpages on HP-UX 11iv3 for further details on scsimgr.


The same information is also documented in page 45 of Veritas Storage Foundation 5.0.1 Release Notes on HP-UX - "Disabling HP_UX native ALUA for arrays operating in ALUA mode (1822365)".