Knowledge Base
Resignaturing VMFS3 volumes from VMware Infrastructure Client
Details
- You recently changed the Host Mode setting on a Hitachi Data System (HDS) storage array
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VMFS3 volumes are seen as snapshot volumes
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Volumes are disabled or missing unexpectedly
- Datastores are missing after SAN upgrade
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Datastores are missing unexpectedly
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You recently set the SPC-2 flag on the EMC Symmetrix storage array
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You recently downgraded the Perc 4e/Di firmware and local datastores are now missing
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/var/log/vmkernel contains the entry:
vmhba0:0:0:1 may be snapshot -
You recently performed the steps contained in On ESX Server Systems with Multiple PERC 4 Controllers, LUNs Become Temporarily Inaccessible After Upgrading the PERC 4 Firmware (5966817)
Solution
Making this type of change on the storage array results in assigning a new LUN ID (UUID or Serial Number) to all LUNs presented via the modified ports/FAs.
VMFS3 metadata identifies the volumes by several properties which include the LUN number and the LUN ID (UUID or Serial Number). Because the LUNs now have new UUIDs, the resulting mismatch with the metadata leads to LVM identifying the volumes as snapshots.
You must resignature the VMFS3 volumes to make them visible again.
Important:
- If you do not have actual snapshot LUNs presented and have no plans to present any to these hosts, follow the directions in VMFS Volume Can Be Erroneously Recognized as a Snapshot (6482648), then skip to step 9 below.
- If you have to resignature a datastore spanned across more than one LUN, you must make sure that all the LUNs that comprise the datastore are in a snapshot state. Failing to do so may result in getting the datastore locked into an inconsistent status, which may require VMware support assistance.
To resignature the VMFS3 volumes in VMware Infrastructure (VI) Client:
Note: You can complete this resignaturing procedure from the command line. For more information, see New ESX host(s) added to cluster are seeing snapshot LUNs despite correct Host LUN ID being presented from the SAN array (1005751).
Caution: This procedure can be time-consuming, depending on the size of the environment. Ensure that you budget time for the outage.
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Shut down all virtual machines running on the datastores recognized as snapshots.
Note: This step is necessary because those datastores are affected by the resignaturing process and it cannot be applied to a datastore that is being used (that is, with active I/O). -
Unregister all of the virtual machines on the affected datastore(s). This can be done from VI Client by right-clicking on the virtual machine and selecting Remove from Inventory.
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Rescan.
Note: The /var/log/vmkernel file contains snapshot messages.
- Enable LVM Resignaturing on the first ESX host:
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Log in to the ESX host with VI Client.
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Click the Configuration tab.
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Select the Advanced setting option.
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Choose the LVM section.
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Set the value of LVM.EnableResignaturing to 1.
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Save the change.
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Click the storage adapter tab.
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Click Rescan Adapter located at the top right corner of the interface.
Note: There is no need to select an HBA. All are rescanned. - Leave the default option and proceed.
You are now able to see the VMFS volumes with labels prefixed with snap.
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- Disable LVM Resignaturing:
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Log on to the ESX host with VI client.
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Click the Configuration tab.
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Select the Advanced setting option.
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Choose the LVM section.
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Set the value of LVM.EnableResignaturing to 0.
- Save the change.
No snapshot messages are visible in /var/log/vmkernel.
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- Re-label the volume.
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- Log in to the VirtualCenter Server with VI Client.
Note: Connecting directly to the ESX host does not offer the view identified in step b.
- Click the arrow next to the Inventory menu option and click Datastores.
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Select the datastore. Right-click and select Remove to remove the old label, which is associated with the old UUID of the volume.
Caution: Ensure that you are in the Datastore view and that the number of connected hosts is 0 (identified in the red outline). For example:
In this example, the highlighted datastore has 6 ESX hosts connected to it. This datastore is active and must not be removed.
Perform a remove process in any other view to remove that active datastore.
- Click the arrow next to the Inventory menu option and click Hosts & Clusters.
- In the Summary tab, you see the list of datastores.
- Click in the name field for the volume and change snap0000 to the original name.
You now have the correct original label associated with the resignatured volume.
- Log in to the VirtualCenter Server with VI Client.
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Rescan storage from all ESX hosts. You do not need to rescan from the host that performed the resignature.
- Because the virtual machines are registered against the old UUID, you must re-register them in VirtualCenter.
To re-register the virtual machine in VirtualCenter:
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Log on to the ESX host with VI client.
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Click the Configuration tab.
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Select Storage (SCSI, SAN & NFS).
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Double-click any of the datastores to open the Datastore browser.
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Navigate to the .vmx file of any of the virtual machines by clicking the folders.
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Right-click and select Add to inventory.
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- Remap any RDMs.
If you have a virtual machine that uses an RDM, you must recreate the mapping.
Caution: If you used multiple RDMs, it may be difficult to identify one from another. If the RDMs are different sizes, you can map them in the correct order by their sizes. If the RDMs are all the same size, this is a more difficult process because you must map the RDMs to one virtual machine at a time, boot the virtual machine, and then verify if it is the correct LUN. To prevent having to map the RDMs to one virtual machine at a time:
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- Make a note of the sizes of the RDMs and which virtual machines they are associated with before starting this process.
- Make a note of the LUN ID before starting this process. You might be able to use this information to recreate the mapping.
- Power on the virtual machines. Reply yes if prompted about a new UUID.
If any of the virtual machines refer to missing disks when they power up, check the .vmx file and ensure that the SCSI disk references are not made against the old UUID instead of against the label (or new label, if you changed it). For more information, see Unable to power on a virtual machine after a volume resignature (1007022).
- Repeat steps 3 through 9 for all subsequent ESX hosts that still see snapshot volumes. If all ESX hosts share the same volumes, this step is not necessary.
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