vSphere 5.1 and vSphere 5.5 changes default Path Selection Policy from VMW_PSP_FIXED to VMW_PSP_RR for EMC arrays using VMW_SATP_ALUA_CX and VMW_SATP_SYMM Storage Array Type Plugins (SATP)
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vSphere 5.1 and vSphere 5.5 changes default Path Selection Policy from VMW_PSP_FIXED to VMW_PSP_RR for EMC arrays using VMW_SATP_ALUA_CX and VMW_SATP_SYMM Storage Array Type Plugins (SATP)

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Article ID: 340033

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Updated On:

Products

VMware vSphere ESXi

Issue/Introduction

Symptoms:
After installing/upgrading to ESXi 5.1, you experience these symptoms:

Note: You see these symptoms when LUNs are mapped as RDMs and used by virtual machines which use MSCS as shared storage in a Cluster Across Boxes (CAB) configuration.
  • The default Path Selection Policy (PSP) is set to Round Robin.
  • The quorum disk experiences problems and the cluster may not operate.

    Note: This issue is not limited to devices or LUNs presented from EMC Storage arrays that use these Storage Array Type Plugins (SATP), VMW_SATP_ALUA_CX and VMW_SATP_SYMM.


Environment

VMware vSphere ESXi 5.0
VMware vSphere ESXi 5.5
VMware vSphere ESXi 5.1

Cause

This issue occurs due to default Path Selection Policy (PSP) is changed when you upgrade host to ESXi 5.1.
When corresponding storage vendors request to change the default claim rules to use VMW_PSP_RR for the storage devices are claimed by the Storage Array Type Plugins (SATP), VMW_SATP_ALUA_CX and VMW_SATP_SYMM
The default Path Selection Policy (PSP) was changed by the upgrade to ESXi 5.1 since the corresponding storage vendors have requested changing the default claim rules to use VMW_PSP_RR for the storage devices that get claimed by the following Storage Array Type Plugins (SATP), VMW_SATP_ALUA_CX and VMW_SATP_SYMM

The default PSP list can be interrogated by running this esxcli command:

esxcli storage nmp satp list

Name Default PSP Description
------------------- ------------- -------------------------------------------
VMW_SATP_ALUA_CX VMW_PSP_RR Supports EMC CX that use the ALUA protocol
VMW_SATP_SYMM VMW_PSP_RR Supports EMC Symmetrix

Resolution

Notes:
  • Round Robin path policy is not supported by Raw Device Mapped LUNs that are used with MSCS in VMware ESXi 5.1.x and older versions. For more information, see Setup for Failover Clustering and Microsoft Cluster Service.
  • Starting with vSphere 5.5, round robin policy is supported for disks engaged in MSCS clustering.

    However, these restrictions apply:

    • Supported on Windows 2008, Windows 2012 and Windows 2012 R2 server guest operating systems only.
    • Supported on Cluster Across Boxes (CAB) and N+1 configurations. Cluster in a box uses Virtual Reservations.
    • Shared disk (Quorum OR Data) must be provisioned to guest in pass-through RDM mode only.
    • Windows 2012 and Windows 2012 R2 cluster validation may fail with "resource busy" error while using PSP_RR. This error can be ignored. For more information, see MSCS support enhancements in vSphere 5.5 (2052238).

  • For a supported configuration, you must change the pathing policy for all devices claimed by VMW_SATP_ALUA_CX and VMW_SATP_SYMM SATPs to Fixed Path Selection Policy (VMW_PSP_FIXED)
To resolve this issue, change the pathing policy to MRU or Fixed using the command-line or vSphere Client.

To change the pathing policy using the vSphere Client:

Connect the vSphere Client to the ESX host or vCenter Server.

  1. Select a host in the left pane and click the Configuration tab.
  2. Under Hardware, click Storage Adapters.
  3. Select a Fiber Channel HBA from the list.
  4. Right-click the LUN for which you want to change the Path Selection Policy and click Manage Paths.
  5. Depending on the type of array, select Fixed or MRU from the Path Selection dropdown.
  6. Repeat these steps for LUNs on each host that is a part of a cluster with MSCS virtual machines.
  7. To change the pathing policy using the command-line, see Changing a LUN to use a different Path Selection Policy (PSP) (1036189).

To change the pathing policy using the vSphere Web Client

  1. In the vCenter Home, navigate to Expand Inventory Trees > Hosts and Clusters.
  2. Click the applicable Datacenter or Cluster and then select the ESXi host you wish to manage.
  3. Click the Manage.
  4. Click the Storage and Storage Devices.
  5. Select your applicable Storage device you wish to modify your Multipath PSP Policy.
  6. Click Properties under Device Details.
  7. Under Multipathing Policies, click the Edit Multipathing
  8. Select Fixed Path from the dropdown menu and click OK

To change the Multipath PSP from command line issue

  1. List the current Multipath PSP for a device by running this command:

    esxcli storage nmp device list -d naa.xxxxx

  2. Change the PSP to FIXED (VMW_PSP_FIXED) issue by running this command:

    esxcli storage nmp device set -d naa.xxxx --psp=VMW_PSP_FIXED


Additional Information

For more information, see:

vSphere 5.1 および 5.5 で "VMW_SATP_ALUA_CX" や "VMW_SATP_SYMM" SATP を使用する EMC 製ストレージ装置でのデフォルトの PSP (パス選択ポリシー) が "VMW_PSP_FIXED" から "VMW_PSP_RR" へ変更される