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rescan ESXi 5.1 storage with dead / error paths

king daddy
king daddy asked

I have some datastores under 'Devices' showing 'dead or error / lost communication' in the vSphere client. They are not under datastores. This is on an HP P2000 G3 and a VNXe 3150. The VNXe is lost communication and the P2000 is dead or error. I cannot find the associated datastores on either SAN. It's like they don't exist. I know some datastores were created, mapped to hosts on the SANs, then deleted from the SANs before rescanning and adding the datastore to the ESXi hosts.

There are no networking issues on any host or either SAN. All VMs are running properly.

My concern is that if I rescan the hosts I will end up in a APD situation because of these errors.

Any insight into how to better troubleshoot this, and specifically, if someone could let me know if I will get an APD if I rescan, is greatly appreciated. To note I have refreshed without issue but not rescanned.

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Top Expert 2014
Doing a rescan can cause ESXi to hang, as it will issue I/O to the datastore which is no more available, this could impact the VMs running on the host.

If you have downtime, I would recommend you to restart the Esxi to see if the issue is resolved.

Further reference:

Permanent Device Loss (PDL) and All-Paths-Down (APD) in vSphere 5.x (2004684)

Planned versus unplanned PDL

A planned PDL occurs when there is an intent to remove a device presented to the ESXi host. The datastore must first be unmounted, then the device detached before the storage device can be unpresented at the storage array.

An unplanned PDL occurs when the storage device is unexpectedly unpresented from the storage array without the unmount and detach being executed on the ESXi host.

To clean up an unplanned PDL:

1. All running virtual machines from the datastore must be powered off and unregistered from the vCenter Server.

2. From the vSphere Client, go to the Configuration tab of the ESXi host, and click Storage.

3. Right-click the datastore being removed, and click Unmount.

4. The Confirm Datastore Unmount window displays. When the prerequisite criteria have been passed, the OK button appears.

If you see this error when unmounting the LUN:

Call datastore refresh for object <name_of_LUN> on vCenter server <name_of_vCenter> failed

You may have a snapshot LUN presented. To resolve this issue, remove that snapshot LUN on the array side.

Perform a rescan on all of the ESXi hosts that had visibility to the LUN.

Note: If there are active references to the device or pending I/O, the ESXi host still lists the device after the rescan. Check for virtual machines, templates, ISO images, floppy images, and raw device mappings which may still have an active reference to the device or datastore.

If the LUN is still being used and available again, go to each host, right-click the LUN, and click Mount.

Note: One possible cause for an unplanned PDL is that the LUN ran out space causing it to become inaccessible.

GG VP - thanks for replying. I ended up finding out that datastores were added to the SANs then deleted before being added to the VMware hosts manually. However, it appears they showed up anyway as they were mapped SAN-side, thus they showed dead / error and lost communication after being unmapped and deleted SAN-side. With that info I decided to rescan after hours and they were promptly removed from vCenter client with no issues.


My solution worked in this case. I awarded points since GG VP actually responded and tried to help me and I appreciate that. Plus his info was pertinent but luckily not needed in this case.