[Qemu-discuss] live migration copies block device into RAM causing OOM

[Tom Denley]

We are trying to use the live migration capability to move VMs off of an
old ubuntu precise (12.04) KVM host.

We are using the --copy-storage-all option to move block devices during the
migration, and it seems that the old version of QEMU (v1.0) on precise
copies the block device into RAM as part of the migration. This typically
results in RAM running out on the host machine causing OOM-killer to shoot
the VM being migrated, and the migration failing.

Is there a way to stop this happening?  It appears not to happen in newer
QEMU versions, so I wonder if it is a bug with the old QEMU version, but I
have been unable to find any mention of one.  Sadly, the entire point of
live migrating VMs off is to allow us to upgrade the host OS to a newer
version.

-- 
Tom Denley