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An Introduction to Full Virtualization With Xen (Linux.com)An Introduction to Full Virtualization With Xen (Linux.com)Posted Oct 24, 2012 13:20 UTC (Wed) by cas (subscriber, #52554)In reply to: An Introduction to Full Virtualization With Xen (Linux.com) by Lennie Parent article: An Introduction to Full Virtualization With Xen (Linux.com)
Remus sounds useful.
For KVM, there's plain old migration.
It's not the same as VM mirroring, but if you don't have the hardware (or the need) for completely transparent VM failover, you can do something similar with virsh save and virsh restore of a currently running VM.
The VM is paused for as long as it takes to save, transfer to another machine, and restore the VM's state.
Works well enough with shared storage (like NFS), and (i haven't tried this) might even work if you save to stdout, pipe over ssh, and then restore from stdin.
Otherwise if the VM or the server it's running on has died, DRBD or iscsi volumes or even qcow2 on NFS can be used to boot a VM on another server.
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An Introduction to Full Virtualization With Xen (Linux.com) Posted Oct 24, 2012 13:50 UTC (Wed) by Lennie (subscriber, #49641) [Link]
Most people don't need something like Remus.
If you want some form of failover it is usually better to have 2 VM's in proper failover configuration. In a way that fits the software involved.
But the question was why Xen, so I thought I'd mention it. :-)
An Introduction to Full Virtualization With Xen (Linux.com) Posted Oct 24, 2012 15:45 UTC (Wed) by Lennie (subscriber, #49641) [Link]
Maybe I should add that Remus does not work well over a WAN-link (you need lowlatency). So you probably can't use it for failover to a different datacenter either.
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