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Setting up active-passive dual pathing with vSAN and vSphere (2151225)

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Purpose

Some enclosures permit more than one path from a node to the drives in use. These are usually dual port SAS drives. A typical arrangement would look similar to:

Single Node --------> Expander A --------> 1 to many SAS Drives Port A
|
------------------> Expander B --------> (same drives as above) Port B
 

The purpose of this arrangement is not to drive IO down on both the paths simultaneously (that would be an active-active arrangement) but to keep the path via Expander B available for seamless, instantaneous failover in case the other path via Expander A fails. This is an active-passive arrangement.

The criteria for this arrangement are as follows:

  1. Instantaneous failover to the secondary path, invisible to the rest of the system (seamless)
  2. Automatic - no operator intervention to make the failover happen
  3. Allow recovery of a path. The recovered path should come back as the passive path with no operator intervention other than repairing the path.
  4. Require simple set up for each node
  5. Require no drive specific settings. Note: Avoid setting this feature for each drive individually.
  6. Support hot plug (drive FRU replacement) without operator intervention to set up on replaced drive
  7. Support soft-configuration changes such as drives added by zoning changes without operator intervention.
  8. Support vSAN and vSphere
  9. Preserve settings across ESXi installation when updating (not installing).

Resolution

This example uses nhpsa as the driver. Replace nhpsa with the driver you are using.
 
Note: The VMKLinux drivers do not add the repaired path back without operator intervention. Therefore, VMware recommended to use ESXi 6.5+ and native drivers.
  1. SSH in to your node. You may need to enable SSH support via the webgui first.
  2. Once SSH is up, run these commands in sequence (replacing the driver name with your driver):
a. esxcli storage nmp satp rule add -D nhpsa -s VMW_SATP_DEFAULT_AP
b. esxcli storage core claiming unclaim -t driver -D nhpsa
c. esxcli storage core claimrule load
d. esxcli storage core claimrule run
After running the preceding commands, the system is set up and should not need further configuration. Additional paths can be added and failed over.

Tags

Active-Passive Dual Pathing, vSAN, vSphere

Keywords

Active-Passive Dual Pathing, vSAN, vSphere

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