Volume Manager “vxdmpadm listenclosure/listctlr” differences for 4.1 to 5.1 with EMC PowerPath

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Article ID: 100004728

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Resolution

VxVM 4.1 specifics

• In releases of Veritas Volume Manager ( VxVM ) before 4.1, a combination of DMP subpaths and the controllers of DMP subpaths were usually suppressed to prevent interference between DMP and the EMC PowerPath multipathing driver.

• Suppression has the effect of hiding these subpaths and their controllers from DMP, and as a result the disks on these subpaths and controllers cannot be seen by VxVM .

• VxVM 4.1 and later releases have the ability to discover EMCpower (pseudo) disks, and configure them as autodiscovered disks that DMP recognizes are under the control of a separate multipathing driver. This has the benefit of allowing such disks to reconfigured in cluster-shareable disk groups.

• Before upgrading to VxVM 4.1, you must remove the suppression of the subpaths and controllers so that DMP can determine the association between EMCpower metadevices and c#t#d # disk devices.

• With the 4.1 release of VxVM , DMP can co-exist with PowerPath . Depending on the scenario, you may need to install the EMC CLARiiON ASL and its associated APM. To use DMP with PowerPath , you should be aware of the following scenarios.

■ If you are installing VxVM 4.1 and PowerPath is installed, you do NOT need to install the CLARiiON ASL and its associated APM. The CLARiiON array must be configured in explicit fail-over mode. Failover Mode “1”

■ If you are installing VxVM 4.1 and PowerPath is NOT installed, you must install the CLARiiON ASL and its associated APM. The CLARiiON array can be configured in either mode(1,2). Traditionally Failover Mode “2” was recommended for DMP, circumstances have since changed.

Third-party driver coexistence

• The third-party driver (TPD) coexistence feature introduced in VxVM 4.1 allows I/O that is controlled by third-party multipathing drivers to bypass DMP while retaining the monitoring capabilities of DMP.

• Provided that a suitable ASL is available, devices that use TPDs can be discovered without requiring you to set up a specification file, or to run a special command.

• In previous releases, VxVM only supported TPD coexistence if the code of the third-party driver was intrusively modified. The new TPD coexistence feature maintains backward compatibility with such methods, but it also permits coexistence without require any change in a third-party multipathing driver.

• The new TPD ASL “ libvxpp.so ” introduced 5.0 MP3 enables the EMC TPD devices to be unmanaged by PowerPath and controller by Veritas DMP.

5.0 (MP1) DMP COEXISTENCE WITH EMC POWERPATH

• With the 5.0 release of VxVM , DMP can co-exist with PowerPath . The main change is that both the “ libvxemc.so and “ libvxCLARiiON.so ” ASL’s are installed by default. The EMC CLARiiON APM “ dmpCLARiiON ” is also installed by default.

■ If you are installing VxVM 5.0 and PowerPath is installed, you no longer need to download the CLARiiON ASL and its associated APM. Both components are installed by default. The CLARiiON array must be configured in explicit fail-over mode. Failover Mode “1”

     ■ If you are installing VxVM 5.0 and PowerPath is NOT installed.. The CLARiiON array can be configured in either mode (1 or 2). Support would now recommend Failover Mode “1” with both DMP and PowerPath , as circumstances have since changed.

libvxemc.so                           = Claims EMC Symmetrix /DMX luns
libvxCLARiiON.so                = Claims EMC CLARiiON luns

■ When PowerPath is configured, all the EMC array type luns are claimed by the libvxemc.so ASL.

VxVM 5.0 MP3 introduced the "libvxpp.so" TPD ASL

• With the SF 5.0 MP3 release of VxVM , DMP can co-exist with PowerPath . Both the “ libvxemc.so and “ libvxCLARiiON.so ” ASL’s are installed by default as before. The EMC CLARiiON APM “ dmpCLARiiON ” is also installed by default as before.

■ The key change is the introduction of the " libvxpp.so " ASL library which handles the TPD (Third Party Driver) claiming mechanism for PowerPath controlled LUNS.

■ As with 5.0, if you are installing VxVM 5.0 and PowerPath is installed, you no longer need to download the CLARiiON ASL and its associated APM. Both components are installed by default. The CLARiiON array must be configured in explicit fail-over mode “1” or "4" depending on the CLARiiON FlareCode and 5.0 MP3 RP patch level.

- If 5.0 MP3 RP1 has been installed; Failover Mode “4” (ALUA) can be set for both PowerPath and DMP. The EMC CLARiiON Flare Code must be a minimum of “26” or higher

libvxemc.so                           = Claims EMC Symmetrix /DMX luns
libvxCLARiiON.so                = Claims EMC CLARiiON luns
libvxpp.so                             = Claims EMC PowerPath managed luns          (NEW)

■ When PowerPath is configured, all the PowerPath managed/controlled (TPD) EMC array type luns are claimed by the libvxpp.so ASL.

- To allow DMP to receive correct enquiry data from EMC Symmetrix/DMX disk arrays, the common Serial Number (C-bit) Symmetrix Director parameter must be set to enabled. .

Sample output

4.1 MP2

# vxdmpadm listctlr all
CTLR-NAME        ENCLR-TYPE       STATE       ENCLR-NAME
=====================================================
emcp             EMC              ENABLED       EMC0
c2                Disk             ENABLED       Disk
emcp             EMC_CLARiiON     ENABLED       EMC_CLARiiON0

# vxdmpadm listenclosure all
ENCLR_NAME         ENCLR_TYPE      ENCLR_SNO       STATUS        ARRAY_TYPE
============================================================================
EMC0               EMC             300822                CONNECTED     A/A
Disk               Disk            DISKS                 CONNECTED     Disk
EMC_CLARiiON0      EMC_CLARiiON    CK200053300424        CONNECTED     A/A

5.0 (MP1) (no change except libvxCLARiiON.so installed by default)

5.0 MP3

# vxdmpadm listctlr all
CTLR-NAME        ENCLR-TYPE       STATE       ENCLR-NAME
=====================================================
emcp             EMC              ENABLED       EMC0
c2               Disk             ENABLED       Disk
emcp             EMC_CLARiiON     ENABLED       EMC_CLARiiON0

5.0 MP3 (NEW ASL “libvxpp.so” & powerpath unmanaged device support)

The key change is the introduction of the "libvxpp.so" ASL library which handles the TPD (Third Party Driver) claiming mechanism for PowerPath controlled LUNS.

# vxdmpadm listenclosure all
ENCLR_NAME        ENCLR_TYPE     ENCLR_SNO      STATUS       ARRAY_TYPE     LUN_COUNT
=======================================================================================
emc0              EMC            000290300822         CONNECTED    A/A         1                 <<<< unmanaged EMC PowerPath LUN
disk              Disk           DISKS                CONNECTED    Disk        4
pp_emc0           PP_EMC         000290300822         CONNECTED    A/A        119
pp_emc_clariion0 PP_EMC_CLARiiON CK200053300424       CONNECTED    A/A         5
pp_emc1           PP_EMC         000290301414         CONNECTED    A/A         8

# vxdmpadm listctlr all
CTLR-NAME       ENCLR-TYPE      STATE      ENCLR-NAME
=====================================================
c3              Disk            ENABLED      disk
c1              EMC             ENABLED      emc0                 <<<< unmanaged EMC PowerPath LUN
emcp            PP_EMC          ENABLED      pp_emc0
emcp            PP_EMC          ENABLED      pp_emc1
emcp            PP_EMC_CLARiiON ENABLED      pp_emc_clariion0

5.1 (no change compared to SF 5.0 MP3)

Issue/Introduction

This document attempts to show the “vxdmpadm listenclosure/listctlr” CLI (command line interface) differences for EMC storage arrays for Veritas Volume Manager (VxVM) releases 4.1 through to 5.1 with EMC PowerPath.

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