race condition? virsh migrate --copy-storage-all

[Valentijn Sessink]

Hi list,

I'm trying to migrate a few qemu virtual machines between two 1G 
ethernet connected hosts, with local storage only. I got endless "error: 
operation failed: migration of disk vda failed: Input/output error" 
errors and thought: something wrong with settings.

However, then, suddenly: I succeeded without changing anything. And, hey:
  while ! time virsh migrate --live --persistent --undefinesource 
--copy-storage-all ubuntu20.04 qemu+ssh://duikboot/system; do a=$(( $a + 
1 )); echo $a; done

... retried 8 times, but then: success. This smells like a race 
condition, doesn't it? A bit weird is the fact that the migration seems 
to succeed every time while copying from revolving disks to SSD; but the 
other way around has this Input/output error.

There are some messages in /var/log/syslog, but not at the time of the 
failure, and no disk errors. These disks are LVM2 volumes and they live 
on raid arrays - and/so there is not a real, as in physical, I/O-error.

Source system has SSD's, target system has regular disks.

1) is this the right mailing list? I'm not 100% sure.
2) how can I research this further? Spending hours on a "while / then" 
loop to try and retry live migration looks like a dull job for my poor 
computers ;-)

Best regards,

Valentijn