You may have a situation where you cannot start your VM in another host in the pool and you cannot live migrate that VM to another host in the pool.
This problem can arise when you use ‘/opt/xenso
Here are some of the errors you may see.
You may get this error in XenCenter:
Internal error: File "xapi_xenops.ml", line 1788, characters 3-9: Assertion failed
Or this error on the CLI:
Error code: SR_BACKEND_FAILURE_46 Error parameters: , The VDI is not available [opterr=VDI 86012149-349d-469d-969d-6ff4ee36595f already attached RW]
The solution is to shut down the VM, forget the VDI-s, rescan the SR and re-attach the VDI-s to the same VM in the same order.
I would suggest doing a full backup of the entire VM before this.
Here is an artice about making a backup of live running VM:
If you have backed up everyhting you needed, then:
1) Stop the VM in XenCenter 2) In cli: xe vdi-forget
3) In cli: xe sr-scan 4) Reattach the VDI to the VM in XenCenter 5) Start the VM in XenCenter