[libvirt-users] Using virsh blockcopy -- what's it supposed to accomplish?

Gary R Hook grhookatwork at gmail.com
Mon Dec 22 22:27:03 UTC 2014


I am experimenting with the blockcopy command, and after figuring out 
how to integrate qemu-nbd, nbd-client and 
dumpxml/undefine/blockcopy/define/et. al. I have one remaining question:

What's the point?

The "replication" disk file is not, from what I can ascertain, bootable. 
I expect this operation to create a pristine copy of my source qcow2 
file (at a given point in time) which implies that I can swap that copy 
in and use it just like the original.

Neither using --finish nor --pivot (both appear successful) give me a 
mirror that seems to serve any purpose. It seems especially pointless if 
I use --pivot because anything that happens after the pivot ends up lost 
if I don't actually have a usable qcow2 file.

I find lots of discussion online about getting the steps to work, but as 
yet find nothing about using the resulting file.

What am I missing here?

libvirt (1.2.2) and qemu (2.2.0) as distributed with Ubuntu Trusty.

-- 
Gary R Hook
Senior Kernel Engineer
NIMBOXX, Inc




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