Multipath Connectivity

UltraPath is a Huawei-developed multipathing software. It can manage and process disk creation/deletion and I/O delivery of operating systems.

UltraPath provides the following functions:

• Masking of redundant LUNs

  In a redundant storage network, an application server with no multipathing software detects a LUN on each path. Therefore, a LUN mapped through multiple paths is mistaken for two or more different LUNs. UltraPath installed on the application server masks redundant LUNs on the operating system driver layer to provide the application server with only one available LUN, the virtual LUN. In this case, the application server only needs to deliver data read and write operations to UltraPath that masks the redundant LUNs, and properly writes data into LUNs without damaging other data.

• Optimum path selection

  In a multipath environment, an application server with UltraPath accesses a LUN on the storage system through an optimum path, thereby obtaining the highest I/O speed.

• Failover and failback
  • Failover

    When a path fails, UltraPath fails over its services to another functional path.

  • Failback

    UltraPath automatically delivers I/Os to the optimal path again after the path recovers from the fault.

• I/O Load balancing

  UltraPath provides load balancing within a controller and across controllers.

  • For load balancing within a controller, I/Os poll among all the paths of the controller.
  • For load balancing across controllers, I/Os poll among the paths of all these controllers.
• Path test

  UltraPath tests the following paths:

  • Faulty paths

    UltraPath tests faulty paths with a high frequency to detect the path recover as soon as possible.

  • Idle paths

    UltraPath tests idle paths to identify faulty paths in advance, preventing unnecessary I/O retries. The test frequency is kept low to minimize impact on service I/Os.

Multiplexed I/O (MPxIO), also known as StorageTek Manager Software (STMS), is a Solaris native multipathing software for storage devices accessible through multiple physical paths. STMS is supported in Solaris 8, 9, 10, and 11.

STMS has the following functional features:

• Manages multipathing configuration.
• Balances I/O load on a group of HBAs.
• Switches paths when links or controllers fail.
• Supports single instance multipath devices.
• Enables dynamic re-configuration.

STMS supports the following load balancing policies:

• Round_robin (default)

  I/Os are concurrently delivered to all paths.

• None

  I/Os are delivered only to one path to a LUN. After the path fails, I/Os are delivered to another path.