Can't delete or unmount datastore

[zenking]

Getting this error when trying to remove datastores.

" Cannot read the host cache configuration because some other process is modifying it at this time."

We aren't using  an ssd for caching, and I've verified there is nothing listed in the host cache configuration for each host. Is it possible there is a running process that needs to be stopped? We've already seen articles on vsantrace (which we don't use) and deleting the DS directly from the host, but still no dice.

Thanks.

[abhilashhb]

You could remove the LUN from storage and then do a rescan. unmount and remove is to safely remove the datastore. You could always remove the LUN and format it

[zenking]

Thanks. I'm reluctant to do that because when the lun is yanked out like that before being removed from the host, the host will continue to try to connect to it and can ultimately freak out and become orphaned from the cluster - ask me how I know -  😞  . Typically I think that's pretty rare and I've successfully done what you suggest, but since the host is preventing the DS from being removed I think it could cause a problem.

I believe I really need to find out why the process is running when host cache isn't configured.

Thanks.

[abhilashhb]

Have you tried a host reboot? Is it an option?

[zenking]

Thanks. I think that's our next thing to try. We're planning to do host updates this week, so we'll see if that clears it up after the reboots.

[CesarTabares]

We had that problem too. But we didn't reboot any hosts. Just waited a few days, and the datastore was possible to unmount, with the standard Unmount option from the VSphere console.

[zenking]

Thanks. We had to reboot anyway after updates, and that cleared it up for us.

[mkwj75]

I had this issue too. I did figure out it was related to another issue we had about a month ago. Last month we were applying some Windows updates to our vCenter and SQL servers. After rebooting the servers, we had one of our 5 VM host refused to reconnect to vCenter. All the VMs were still running but the host just wasn't communicating with vCenter. One article I read said to bounce the hostd and xpxa services. After that was done, the hostd daemon kept crashing. This made it impossible to connect to the host via the vSphere client. Fortunately, I had already turned on SSH before all of that. What caused the hostd daemon to crash was a full ramdisk. That was caused by a log that was consuming the ramdisk entirely. That log was for CIMPLE which is used by many hardware manufactures to establish communication between vSphere and CIM sensors. Truncating the log to free up space on the ramdisk fixed the issue.

Fast forward to yesterday, I was having the issue with unmounting a LUN from vSphere which returned the "cannot read the host cache configuration because some other process is modifying it at this time". Two of my VM Hosts were the issue. After reading you comment that rebooting the host resolved the issue, I remembered that would clear the ramdisk. I check on the ramdisk on both of those Hosts and they were full. I truncated that log and I was able to unmounts and delete that LUN.