SR_BACKEND_FAILURE_453(, tapdisk experienced an error [opterr=Permission denied], ) (SOLVED)

Hi Guys,

just wondering if anyone else has hit this one. I’ve just upgrade my FreeNAS to TrueNAS 12.0. Its being used as an NFS shared storage box for two XCP-NG 8.1 servers, and now, when I try and start any of the VM’s on the shared storage I’m getting the tapdisk error.

I have NO idea why this is the case. All of the permissions look to be OK, XCP-NG seems to be able to connect to the disk OK and see what’s on it, but none of the machines will run.

I’m not ever sure if its an XCP error or a TrueNAS issue.

This stuff seems to be VERY fragile. Every time I try and upgrade something it breaks somewhere.

I have set the permissions on the storage to a+rwx every where I can find them.

Interestingly, when I first tied to do that, I got

Oct 24 13:10:06 cwpstorage 1 2020-10-24T13:10:06.311023+10:00 mountd 2151 - - can’t open /etc/zfs/exports
Oct 24 13:10:06 cwpstorage 1 2020-10-24T13:10:06.405770+10:00 mountd 2151 - - can’t open /etc/zfs/exports
Oct 24 13:10:16 cwpstorage 1 2020-10-24T13:10:16.368608+10:00 mountd 2151 - - can’t open /etc/zfs/exports
Oct 24 13:10:16 cwpstorage 1 2020-10-24T13:10:16.503037+10:00 mountd 2151 - - can’t open /etc/zfs/exports

In the console. That file didn’t exist, so I created it, the warnings went away, but nothing has changed.

Any ideas?

As the error says, it was a permissions error.

The upgrade had changed the owner to some funky number and set the permissions so that they were no longer a+rwx.

Changed that on the storage volumes, and all good again.


had the same problem in vmware with nfs, when upgrade to Truenas 12, due to host downtime i reverted back to Freenas 11.3u5.

Used this:

Or in my case, just like with drama with my share drive CIF, just got an RPG and blew off the front door.

chmod -R 777 unique number found in my NFS dataset

Quoted for truth. I don’t understand all of these tech channels that report back upgrading without issues- there is always some major issues. I can’t update certain jails, plugins and my Xen VMs are toast until changing the permissions.

I suppose some forum goers and even some channels run vanilla setups, in which case the upgrade seems to go off without a hitch. But if you are leveraging above vanilla features, it gets hairy.

@LTS_Tom I have a dumb question, changing the permissions to wide open for that NFS dataset used by Xen (recursive to the .vhd files found within), that has no consequence to the permissions found inside of the OS’s being virtualized correct?