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Objective 1.3 – Configure and Manage Complex Multipathing and PSA Plug-in


  • Explain the Pluggable Storage Architecture (PSA) layout

Skills and Abilities

  • Install and Configure PSA plug-ins
Pluggable Storage Architecture(PSA) is made up of  4 smaller modules which are:
NMP – Native Multipathing (Generic VMware multipathing module)
MPP – Multipathing Plugin
PSP – Path Selection Plugin (handles path selection ie Load Balancing)
SATP – Storage Array Type Plugin (Handles Path failover for a given storage array)
To list the SATP’s log into the ESXi host via SSH (can also be done from vMA with the correct options)
~ # esxcli storage nmp satp list
Name                 Default PSP    Description
-------------------  -------------  -------------------------------------------------------
VMW_SATP_ALUA        VMW_PSP_MRU    Supports non-specific arrays that use the ALUA protocol
VMW_SATP_MSA         VMW_PSP_MRU    Placeholder (plugin not loaded)
VMW_SATP_DEFAULT_AP  VMW_PSP_MRU    Placeholder (plugin not loaded)
VMW_SATP_SVC         VMW_PSP_FIXED  Placeholder (plugin not loaded)
VMW_SATP_EQL         VMW_PSP_FIXED  Placeholder (plugin not loaded)
VMW_SATP_INV         VMW_PSP_FIXED  Placeholder (plugin not loaded)
VMW_SATP_ALUA_CX     VMW_PSP_FIXED  Placeholder (plugin not loaded)
VMW_SATP_SYMM        VMW_PSP_FIXED  Placeholder (plugin not loaded)
VMW_SATP_CX          VMW_PSP_MRU    Placeholder (plugin not loaded)
VMW_SATP_LSI         VMW_PSP_MRU    Placeholder (plugin not loaded)
VMW_SATP_DEFAULT_AA  VMW_PSP_FIXED  Supports non-specific active/active arrays
VMW_SATP_LOCAL       VMW_PSP_FIXED  Supports direct attached devices
The following command is to list out the multipathing modules installed, (as this is the basic install only the NMP should be listed)
~ # esxcli storage core plugin list
Plugin name  Plugin class
-----------  ------------
NMP          MP

Setting your own NMP SATP rule, can be used to change either the default for a device or to make your own. The below command assigns VMW_SATP_DEFAULT_AA satp to storage with vendor HP and Model HSV450 by default this storage would be given VMW_SATP_AULA (not saying this is something you do its just an example)

# esxcli storage nmp satp rule add -V HP - M HSV450 -s VMW_SATP_DEFAULT_AA

Now to change the default PSP of a SATP, This is generally something you would do to change any Active/Active array from the default of VMW_PSP_FIXED to VMW_PSP_RR.

# esxcli storage nmp satp set -s VMW_SATP_SYM -P VMW_PSP_RR

Vendors can supply their own MPP which is basically the whole stack removing completely away from the NMP or they can supply PSP or SATP plugins that fit within the NMP that VMware provides. To install these plugins we can use command line or VUM.

Installing via CLI:

# esxcli software vib install -d file:/<location>/<vendor file>

Installing via VUM just upload as a patch and attached to or create a baseline, check compliance then remediate.

  • Understand different multipathing policy functionalities
    • Most Recently Used (MRU) – This is the default policy for Active/Passive arrays. This policy will select the first working path at boot time and will continue to use that path untill there is a failure, It will then fail to the next available path, it will then stay on that path until there is a failure. MRU has no preferred path and will not fail back if the previous path it was working on returns. If the array supports AULA the storage array will choose the best path initially.
    • Fixed (Fixed) – This is the default for Active/Active arrays. Fixed will use the first active path discovered at boot unless a preferred path has been designated. The the preferred path was to go down it would then fail over to the other active path. This will then fail back to the preferred path when it becomes available again.
    • Round Robin (RR) – This policy enables use of all active paths by rotating through all available paths. This is really the policy to use on an Active/Active array allows the balance the load over all active paths and stops any one path from being overloaded while another sits idle.
  • Perform command line configuration of multipathing options

I covered this in the previous point Install and Configure PSA plug-ins

  • Change a multipath policy

I covered this in the previous point Install and Configure PSA plug-ins

  • Configure Software iSCSI port binding

This can be covered in both command line and vSphere client.
Command Line:
List Uplinks available for use with software iSCSI

#esxcli swiscsi nic list

Connect iSCSI initiator to VMKernel ports

#esxcli swiscsi nic add -n <portname> -d <vmhba33>

Disconnect iSCSI from VMKernel port

#esxci swiscsi nic remove -n <portname> -d <vmhba33>

From the client:

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