Knowledge Base

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 (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 (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:
   
   
   • Resignaturing VMFS3 volumes on VMware ESX 3.x via the VMware Infrastructure Client (9453805) 
   • vSphere handling of LUNs detected as snapshot (1011387)
     
     
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).
   
   
5. Verify that the LUN is not being masked by the ESX Server. For more information, see:
   
   
   • Identifying LUNs masked by ESX 3.x (1004044) 
   • Masking a LUN from ESX and ESXi 4.x using the MASK_PATH plug-in (1009449)
     
     
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:

• Collect the VMware support information. For more information, see  Collecting diagnostic information for VMware products (1008524).
• File a support request with VMware Support and quote this Knowledge Base article ID (1003964) in the problem description. For more information, see How to Submit a Support Request .