Dell Storage Manager 2020 R1 Administrator's Guide

Live Volume ALUA Optimization Considerations

Live Volume ALUA is used to control the priority of paths for the Primary and Secondary Live Volume components. By default, volume mapping is Active/Optimized on the primary volume path and Active/Non-optimized on the secondary volume path. This section provides information about the design features of Live Volume ALUA.

• ALUA is Automatically enabled: Live Volume ALUA is automatically applied when creating Live Volumes in any of the following circumstances. Both the primary and secondary Storage Centers must support ALUA optimization.
  • Creating a new Live Volume
  • Converting a replicated volume to a Live Volume
  • Converting an existing volume to a Live Volume
  • Creating a Live Volume from a restore point (The restore point does not retain the new optimized ALUA information.)

  When a Live Volume is created, the Report Non-optimized Paths feature is enabled by default.

• ALUA is not automatically enabled Live Volume ALUA is not automatically enabled under the following circumstances:
  • Swapping Roles. However if ALUA is enabled on one or more of the systems, that status is reported and persists.
  • Existing Live Volumes after system upgrades. Use the ALUA optimization wizard to enable Live Volume ALUA.
• ALUA Optimization Wizard: If one or more Live Volumes are not ALUA optimized, a message is displayed in a banner at the top of the Live Volume tab in the Replications & Live Volumes view. Clicking the Update to ALUA Optimized link in the banner opens the ALUA optimization wizard. The wizard provides a guided process to enable ALUA optimization on existing Live Volumes.
  NOTE:The system must undergo a service outage (such as server rescans or reboots) to fully enable Live Volume ALUA support. This requirement is due to the path information memory of Multipath Input Output (MPIO) drivers on various servers. Because it is a disruptive operation, enabling Live Volume ALUA on existing Live Volumes should be performed during a maintenance window.
• Non-optimized path reporting Non-optimized path reporting is enabled or disabled using one of these methods:
  • In the ALUA Optimization Wizard: Disable or enable non-optimized path reporting by selecting or clearing the Report Non-optimized Paths check box (see Enable Live Volume ALUA Optimization).
  • In the Edit Live Volume Settings dialog box: Enable or disable non-optimized path reporting by clearing or selecting the Report Non-optimized Paths check box (see Enable or Disable Non-Optimized Path Reporting).
• Microsoft Windows Environments: Using non-optimized paths is not recommended in Microsoft Windows environments and reporting non-optimized path reporting should be disabled. When all paths are reported as non-optimized, MPIO drivers do not function in a round-robin as expected. Data transfer is reduced to a single path causing a delayed failover.
  NOTE:Certain Windows Server 2016 versions can support non-optimized path reporting properly. For more information and best practice guidelines for configuring MPIO on Microsoft Server 2016, see the Dell EMC SC Series Storage and Microsoft Multipath I/O white paper on the Dell support site.