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Thursday, 9 January 2014

Path redundancy to the storage device is degraded (1009555)


You are experiencing these issues:
  • ESX host has lost a redundant path to a storage device and there are still more than one active paths left
  • The Task and Events tab of the ESX host on the vSphere Client reports the error:

    Path redundancy to storage device DeviceName degraded. Path vmhbaN:Cx:Ty:Lz is down. Affected datastores: DatastoreName
  • ESX host and virtual machines continue to access the storage device through the remaining active paths


If vmhba3:C0:T1:L7, which is one of the many active paths to a specified storage device, goes down, you see the message:

Path redundancy to storage device naa.60a9800043346534645a433967325334 degraded. Path vmhba3:C0:T1:L7 is down. Affected datastores: Datastore1
The situation indicates a single point of failure and poses a performance impact in the virtual machines currently accessing the storage device.
The storage device reading vmhba3:C0:T1:L7 in the example contains several potential failure points:
  • vmhba35 - HBA (Host Bus Adapter)
  • C1 - Channel
  • T0 - Target (Storage processor port)
  • L7 -  LUN (Logical Unit Number or Disk Unit)
To determine the actual failure or to eliminate possible issues:
  1. Identify the available storage paths to the reported storage device by running the esxcfg-mpath -l command. For more information, see Obtaining LUN pathing information for ESX hosts (1003973).
  2. Check that a rescan does not restore visibility to the targets. Follow the steps in Performing a rescan of the storage (1003988) to rescan the storage device by using the command-line interface and VMware vSphere Client.
  3. Determine whether the connectivity issue is with the iSCSI storage or the fiber storage. Perform one of these options depending on what your connectivity issue is:
  4. Check the physical hardware, including:
    • The storage processors on the array
    • The fiber switch and the Gigabit Interface Converter (GBIC) units in the switch
    • The fiber cables between the fiber switch and the array
    • The array itself
Important: A rescan is required after any change is made to see if the targets are detected.