i guess we can mix up the DRBD shared storage emulation (http://www.drbd.org
) with virtualbox raw disk drive support to achieve a very complete and enterprise shared storage like experience (given a performance reduction since DRBD just EMULATES the shared storage).
You can sit the emulated disk on the DRBD exported device, set a two-primaries behaviour among the two hosts (we can imagine more than two hosts, but let's start with the simple thing), and start the VM on the first host.
The guest OS will happily perform I/O on the DRBD device as if it were a normal local hdd, and DRBD mirrors everything from the first host to the second host system. Then we start the live migration, and the second host receives the teleporting info and start executing the virtual machine with exactly the same data available to the first system.
Since it's a two-primaries scenario, the second host will send modification done by guest OS to the raw device back to the first host, keeping the actual disc in perfect sync (unless something gets broken, at least).
- Simple to understand
- REALLY COOL
- Need the replication cable with a fast network (Gigabit Ethernet at least, better a twin Giga)
- Not so simple to implement
- Need for a messagging framework to avoid split brain conditions (heartbeat with no services should run fine)
- Need for a DRDB device for any disc of any machine, and config accordingly. Would lead to a bunch of partition on real devices OR lvm usage and configuration to avoid too much partitions. Easy to break config when number of devices grows, and a bunch of TCP connections on the cable (1 for disc).
- I've not yet tested it... but it should work..