LUN Removal Reconfiguration Guidelines

Description

This document outlines the required multi-step LUN removal guidelines when removing access to a LUN from a Solaris Sparc environment
 

KEY POINTS:

• VxVM must be informed that the intended disk is being removed to ensure the cfgadm (Leadville stack) correctly reflects the access path state: unusable
  
  
• Adding and removing devices must be done at different times, and not under the same reconfiguration event
  
  
• Prior to adding or removing devices, the cfgadm -alo show_FCP_dev output should always be checked for existing failing or unusable access path states

MULTI-STEP REMOVAL PROCESS:

When intentionally removing a LUN from a server, VxVM must be informed prior to any storage activity

1.      The Veritas disk access (da) name should be offlined in the event that the entire LUN is being removed
 

         # vxdisk offline <disk-access-name>

2.      The Veritas disk access name should be marked for removal using:

         # vxdisk rm <disk-access-name>

The above command informs & prepares VxVM to remove the specified Veritas disk access (da) name from the system

NOTE: The above commands are not to be performed if we are only removing paths of a LUN and not the entire LUN

Visual Illustration:

3.       In addition, the DMP paths for the Veritas access name should also be disabled using:

           # vxdmpadm -f disable dmpnodename=<da-name>

4.       Perform Storage array activity to remove LUN from Solaris server

The Peripheral Qualifier/Device Type (PQ) attribute will report a non-zero value when the LUN has been intentionally removed at the Storage Layer:

Sample command:

# /etc/vx/diag.d/vxscsiinq -d /dev/vx/dmp/emc0_00aa | head -3

Inquiry for /dev/vx/dmp/emc0_00aa, evpd 0x0, page code 0x0
Peripheral Qualifier/Device Type : 3f

5.       Verify the cfgadm -alo show_FCP_dev output reports the intended unusable access path state

          # cfgadm -alo show_FCP_dev

NOTE: If the cfgadm output reports a failing state for any device, something has gone wrong with the process

The luxadm -e offline should be used to correct any access paths reporting a failing state 
 

NOTE: The luxadm interface has been marked as obsolete in Solaris 11.4

The next sequence consists of two commands which perform different actions against the OS devices nodes and /dev links

6.       The OS device node handles (representation of devices in the kernel) must be manually deleted when a LUN is removed from a server

          # cfgadm -o unusable_SCSI_LUN -c unconfigure c#::<wwn>  

7.        The “devfsadm –Cvc disk” command should now be used to clean-up any stale /dev links 

           # devfsadm -Cvc disk

8.       Refresh the VxVM device tree using “vxdisk scandisks” command

When the VxVM vxdisk scandisks CLI command is triggered, VxVM will perform a reconfiguration event

• During the reconfiguration process, VxVM will compare the old DMP/VxVM database (which contains stale entries) with the newly discovered database content
  
• If device paths have been removed or added, DMP will act accordingly
  
• A reconfiguration event will then be triggered which will delete (remove) the DMPNODE or the paths associated with the DMPNODE

# vxdisk scandisks

9.       If the vxnotify file contains “regeneration of device names is required” then execute the command “vxddladm assign names”.

          # vxddladm assign names

The reconfiguration events are recorded in the /etc/vx/dmpevents.log, if the vxesd (eventsource) daemon is running

DMPDR TOOL:

The process can be automated using the DMPDR tool:

# /usr/lib/vxvm/voladm.d/bin/dmpdr -o refresh

SOLARIS SPARC: Dynamic LUN addition and removal made easy with 'dmpdr -o refresh'

https://www.veritas.com/support/en_US/article.100039198


Related Articles:
 

SOLARIS: LUN Addition Reconfiguration Guidelines

https://www.veritas.com/support/en_US/article.100044058


SOLARIS: How to convert the cfgadm failing state to the intended unusable state

https://www.veritas.com/support/en_US/article.100044068