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Troubleshooting VMFS-3 datastore issues (1003964)

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  • LUN is visible but the datastore is not available in /vmfs/volumes
  • Virtual machines fail to power on
  • Running virtual machines may stop responding, fail, or generate an error on a blue screen
  • The ESX host becomes disconnected from VirtualCenter
  • You see these warnings:

    • WARNING: LVM: 4844: vmhbaH:T:L:P detected as a snapshot device. Disallowing access to the LUN since resignaturing is turned off.
    • Date esx vmkernel: Time cpu3: 10340 SCSI: 5637: status SCSI LUN is in snapshot state, rstatus 0xc0de00 for vmhba1:0:6. residual R 999, CR 8-, ER3.
    • Date esx vmkernel: Time cpu3: world ID SCSI 6624: Device vmhba1:0:6. is a deactivated snapshot.


This article provides steps to troubleshoot issues when the VMFS-3 datastore does not mount.

Note: This article is intended only for audiences with version ESX/ESXi 4.x and below.  With ESXi 5.x VMFS-5 has been introduced.  For more information and troubleshooting steps on VMFS-5 see vSphere 5 FAQ: VMFS-5 (2003813).


Validate that each troubleshooting step below is true for your environment. The steps will provide instructions or a link to a document, for validating the step and taking corrective action as necessary. The steps are ordered in the most appropriate sequence to isolate the issue and identify the proper resolution. Please do not skip a step.

  1. Verify that the LUN is presented to the ESX Server host. For more information, see Troubleshooting LUN connectivity issues (1003955).

  2. Verify that the LUN is not being detected as a deactivated snapshot. For more information, see LUN is incorrectly detected as a snapshot on ESX 3.0 and 3.5 hosts (1002351).

  3. Verify that the datastore is not being detected as a snapshot. For more information, see VMFS Volume Can Be Erroneously Recognized as a Snapshot for ESX 3.0 and 3.5 (6482648)

    Note: A resignature may have occurred, leaving certain ESX Server hosts believing that the LUN is now a snapshot. If you decide to perform a resignature, plan a major outage window to do this. For more information, see:

  4. Verify that the LUN is not larger than 2TB/2047GB. This can occur if a LUN is extended. For more information, see Troubleshooting a LUN that is extended in size past the 2TB/2047GB limit (1004230) and KB 2007328.

  5. Verify that the LUN is not being masked by the ESX Server. For more information, see:

  6. Verify that write caching is not disabled on the array. This is verified using the storage array management interface. Consult your storage array vendor if you require assistance. For more information, see  Write-cache disabled on storage array causing performance issues or failures (1002282).

  7. Verify that the partition type for the VMFS-3 partition is set to fb. For more information, see Unable to access the VMFS datastore when the partition is missing or is not set to type fb (1002168).

If the issue continues to exist after trying the steps in this article:


cannot-power-on-vm vm-power-on-fails lun-connectivity

See Also

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