[libvirt-users] Semantics of "virsh migrate --copy-storage-all" vs. --copy-storage-inc

[Andreas Buschmann]

Hello,

what is really the difference between 
  virsh migrate --copy-storage-all
and 
  virsh migrate --copy-storage-inc
?

There are some documents talking about NBD snapshots, but the user
visible semantics are incomplete.

Where does the incremental stuff happen?
Does it require qcow2 files?
Does it work with raw files?
Does "--copy-storage-inc" require existing snapshots?
Does "--copy-storage-inc" require existing snapshots which are in an
external file so that there is a visible chain [base] <- [sn1] <- [sn2]


Background:
I am trying to understand what really happens, so I can use the tools
for a reasonable fast failover between two servers with local storage.

more Background:
I have VMs and bare metal servers which do use expensive shared storages
like NetApp, EMC² VNX, HP and others, but the shared storage boxes all
require customer visible maintenance downtimes every 12 to 20 month.
And these downtimes take a long lead time and are between 01:00 and 05:00.

					Mit freundlichen Gruessen
						Andreas Buschmann
-- 

Andreas Buschmann
[Senior Systems Engineer]

net.DE AG