Message: 20
Date: Mon, 17 Mar 2014 16:05:17 +0100
From: Sebastien Han <sebastien.han@xxxxxxxxxxxx>
To: "Don Talton (dotalton)" <dotalton@xxxxxxxxx>
Cc: "ceph-users@xxxxxxxxxxxxxx" <ceph-users@xxxxxxxxxxxxxx>
Subject: Re: qemu non-shared storage migration of nova
instances?
Message-ID: <86ED699A-DE8B-4864-860F-E324A6F11CC5@xxxxxxxxxxxx>
Content-Type: text/plain; charset="windows-1252"
Hi,
I use the following live migration flags: VIR_MIGRATE_UNDEFINE_SOURCE,VIR_MIGRATE_PEER2PEER,VIR_MIGRATE_LIVE,VIR_MIGRATE_PERSIST_DEST
It deletes the libvirt.xml and re-creates it on the other side.
We use this setup (local direct-attached ephemeral storage and Ceph for persistent volumes) in a production OpenStack cloud. The biggest problem (which I think is still present with newer Qemu&Libvirt, though we are on 1.0 and 1.1.1 respectively at the moment) with this is that live-block-migrations copy all block device contents from source to destination... i.e., even volumes get transferred in a ridiculous sequence of "source hypervisor reads blocks from storage cluster -> source hypervisor streams blocks to destination hypervisor -> destination hypervisor writes blocks back to the storage cluster".
Is that something others have run into and found workarounds for?
Cheers,
~Blairo
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